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United States’ sales of mungbean ( Vigna radiata L. Wilczek) products and other plant-based protein sources exceeded $1 billion in 2020. Most mungbean consumed in the United States is imported, but it has considerable potential as a domestic crop. Its heat and drought tolerance give U.S. farmers an alternative to soybean and corn crop rotation. Mungbean is a 60- to 90-day crop with similar equipment needs, chemical inputs, and storage requirements to those of soybean and has a developed market. Its vulnerability to diseases in the United States is unknown. Thus, we compared the susceptibility of 10 mungbean genotypes to 8 soybean diseases in the lab. We also monitored disease occurrence in sentinel field plots in Iowa. Mungbean accessions showed a wide range of susceptibility to Cercospora kikuchii, Colletotrichum gloeosporioides, Diaporthe caulivora, Fusarium oxysporum, F. virguliforme, Macrophomina phaseolina, Pythium sylvaticum, and Sclerotinia sclerotiorum. Symptoms of frogeye leaf spot, sudden death syndrome, and Rhizoctonia root and crown rot, common soybean diseases, were observed on mungbean in the field; isolates were identified as Cercospora sojina, F. virguliforme, and Rhizoctonia solani, and Koch's postulates were conducted. C. sojina and F. virguliforme are newly reported as causing disease in field-grown mungbean.

Seven new Entomocorticium species (Peniophoraceae) are described based on morphology and phylogenetic analyses. Along with the type species (E. dendroctoni), Entomocorticium comprises eight species of nutritional symbionts of pine bark beetles in North America. Entomocorticium cobbii is the mycangial associate of the southern pine beetle, Dendroctonus frontalis, and E. parmeteri is the mycangial associate of the western pine beetle, D. brevicomis. Entomocorticium whitneyi, E. portiae, E. kirisitsii, E. oberwinkleri and the previously described E. dendroctoni have been isolated from galleries of D. ponderosae and D. jeffreyi in western North America. Entomocorticium sullivanii forms an ambrosia-like layer of basidia and basidiospores in the pupal chambers of Ips avulsus in the southeastern USA. Entomocorticium is phylogenetically placed within Peniophora, a corticioid genus of wood decay fungi with wind-dispersed basidiospores. At least four species of Entomocorticium produce basidiospores on basidia with reduced sterigmata that apparently do not forcibly discharge basidiospores. Another basidiomycete, Gloeocystidium ipidophilum, was described from Ips typographus galleries in Europe, but it is phylogenetically and taxonomically placed in another genus of wood decay fungi as Cylindrobasidium ipidophilum (Physalacriaceae). The free-living wood-decay fungus Phlebiopsis gigantea (Phanerochaetaceae) has been occasionally associated with bark beetles but is unrelated to C. ipidophilum or Entomocorticium.

The spatial dissemination of three prevalent taxa of sooty blotch and flyspeck (SBFS) fungi under several levels of precipitation was compared during 2015 and 2016 in an Iowa apple orchard. Overhead irrigation was used to supplement ambient precipitation in order to insure SBFS spore dissemination and colony development. There were five irrigation levels, involving 1-min-long periods of irrigation that were imposed either once or twice per hour at intervals of 3, 6, or 12 h, as well as a nonirrigated control. Preselected apple fruit were inoculated with one of the three SBFS taxa to serve as sources of inoculum. Dissemination from these inoculated apple fruit was assessed at harvest by counting SBFS colonies on water-sprayed and nontreated fruit. As a further control, additional fruit were enclosed in fruit bags throughout the fruit development period. In both 2015 and 2016, the number of colonies of the SBFS fungus Peltaster gemmifer per apple increased sharply as the duration of irrigation increased, whereas the number of colonies of Microcyclosporella mali increased to a lesser extent and Stomiopeltis sp. RS1 showed no increase. In 2015, the linear relationship between the duration of irrigation-imposed precipitation levels and the number of colonies on the water-sprayed apple fruit was similar for P. gemmifer (slope = 0.09), Stomiopeltis sp. RS1 (slope = 0.07), and Microcyclosporella mali (slope = 0.13); whereas, in 2016, the slope was higher for P. gemmifer (0.28) than for Stomiopeltis sp. RS1 (−0.09) or M. mali (0.06). The results indicated that dissemination of P. gemmifer increased sharply in response to increased irrigation-imposed precipitation, and that dissemination patterns differed considerably among the three SBFS taxa. The apparent advantage of P. gemmifer in precipitation-triggered dissemination may stem from its ability to produce spores rapidly by budding. To our knowledge, this is the first article to assess splash dispersal by SBFS fungi in the field and the first to document taxon-specific patterns of dissemination in this pathogen complex.

Sooty blotch and flyspeck (SBFS) fungi infect the cuticle of fruit, including apple fruit, and produce pigmented colonies. A new member of this fungal complex in the genus Peltaster is described on the basis of molecular and morphological evidence. The SBFS complex is a diverse group of ectophytic fungi that reside primarily within the order Capnodiales. Sooty blotch and flyspeck isolates from apple orchards in the central United States were subjected to parsimony and Bayesian analyses based on the internal transcribed spacer regions of nuc rDNA, the partial translation elongation factor 1-α gene, and the partial mitochondrial small subunit rRNA gene. Phylogenetic analysis delineated a new species, Peltaster gemmifer, from P. cerophilus and P. fructicola. Peltaster gemmifer conidiophores bear primary conidia that produce secondary conidia either through budding or through microcyclic conidiation; these were not seen in cultures of P. cerophilus and P. fructicola. On cellulose membrane that was placed on water agar amended with apple juice, P. gemmifer produced brown to black pycnothyria in a superficial brownish mycelial mat, similar to the colonies produced on apple fruit. Findings from the present study add to the80 named and putative SBFS species so far described worldwide.

Soybean vein necrosis virus (SVNV), a tospovirus and one of the most widespread soybean viruses in North America, is primarily transmitted by soybean thrips (Neohydatothrips variabilis). Although soybean is not considered the primary plant host for SVNV, there is a dearth of knowledge about alternative host plants for SVNV. We therefore investigated whether commonly present specialty and cover crops in Iowa can serve as alternative hosts for SVNV. Seventeen cover crops and seven specialty crops were tested using mechanical and thrips inoculations. Clear symptoms of SVNV and systemic infection in buckwheat and clear local infection with possible systemic infection on melon were shown. Additionally, we compared soybean thrips feeding on 18 cover crops and determined that they preferred alfalfa, buckwheat, crimson clover, and red clover. Our results suggested that alternative host crops may harbor SVNV and be a possible source of inoculum for soybean.

A warning system for the sooty blotch and flyspeck (SBFS) fungal disease complex of apple, developed originally for use in the southeastern United States, was modified to provide more reliable assessment of SBFS risk in Iowa. Modeling results based on previous research in Iowa and Wisconsin had suggested replacing leaf wetness duration with cumulative hours of relative humidity (RH) ≥97% as the weather input to the SBFS warning system. The purpose of the present study was to evaluate the performance of a RH-based SBFS warning system, and to assess the potential economic benefits for its use in Iowa. The warning system was evaluated in two separate sets of trials—trial 1 during 2010 and 2011, and trial 2 during 2013–2015—using action thresholds based on cumulative hours of RH ≥97% and ≥90%, respectively, in conjunction with two different fungicide regimes. The warning system was compared with a traditional calendar-based system that specified spraying at predetermined intervals of 10 to 14 days. In trial 1, use of the RH ≥97% threshold caused substantial differences between two RH sensors in recording number of hours exceeding the threshold. When both RH thresholds were compared for 2013–2015, on average, RH ≥90% resulted in a 53% reduction in variation of cumulative hours between two identical RH sensors placed adjacent to each other in an apple tree canopy. Although both the SBFS warning system and the calendar-based system resulted in equivalent control of SBFS, the warning system required fewer fungicide sprays than the calendar-based system, with an average of 3.8 sprays per season (min = 2; max = 5) vs. 6.4 sprays per season (min = 5; max = 8), respectively. The two fungicide regimes provided equivalent SBFS control when used in conjunction with the warning system. A partial budget analysis showed that using the SBFS warning system with a threshold of RH ≥90% was cost effective for orchard sizes of >1 ha. The revised warning system has potential to become a valuable decision support tool for Midwest apple growers because it reduces fungicide costs while protecting apples as effectively as a calendar-based spray schedule. The next step toward implementation of the SBFS warning system in the North Central U.S. should be multiyear field testing in commercial orchards throughout the region.

Batzer, J. C., Gleason, M. L., Weldon, B., Dixon, P. M., and Nutter, F. W., Jr. 2002. Evaluation of postharvest removal of sooty blotch and flyspeck on apples using sodium hypochlorite, hydrogen peroxide with peroxyacetic acid, and soap. Plant Dis. 86:1325-1332. Postharvest dips of apples (Malus × domestica) in commercial disinfestants were used to remove signs of the flyspeck (FS) pathogen, Schizothyrium pomi, and the sooty blotch (SB) complex (Peltaster fructicola, Leptodontium elatius, and Geastrumia polystigmatis). Apples were dipped for 7 or 15 min in buffered sodium hypochlorite (Agclor 310 plus Decco 312 Buffer) at 200, 400, 500, 600, or 800 ppm chlorine, a mixture of hydrogen peroxide and peroxyacetic acid (Tsunami 100) at 60 ppm/80 ppm, 120 ppm/160 ppm, or 360 ppm/480 ppm, respectively, or soap (Kleen 440), then brushed and rinsed for 30 s on a commercial grading line. Disease severity was assessed as percent diseased area using a quantitative rating system, and by counting the number of colonies of three mycelial types of SB and FS. Percent diseased area on apples was converted to USDA apple grade ratings and retail values. Both assessment methods provided similar results, but the percent-diseased-area method was less labor intensive. A 7-min dip in 800 ppm chlorine resulted in a mean increase from 25 and 55% to 100% Extra Fancy grade for ‘Jonathan’ and ‘Golden Delicious’ apples, respectively, and increased market value by 31 and 14%, respectively. The 7-min, 200-ppm chlorine dip resulted in an increase from 28 and 45% to 92.5 and 96.5% Extra Fancy after treatment for ‘Jonathan’ and ‘Golden Delicious’, respectively. Blemishes were removed more effectively from ‘Jonathan’ and ‘McIntosh’ apples than from ‘Golden Delicious’. Mycelial types of the sooty blotch and flyspeck fungi were removed differentially by the disinfestant dip treatments.

To determine the effect of sensor placement on the performance of a disease-warning system for sooty blotch and flyspeck (SBFS), we measured leaf wetness duration (LWD) at 12 canopy positions in apple trees, then simulated operation of the disease-warning system using LWD measurements from different parts of the canopy. LWD sensors were placed in four trees within one Iowa orchard during two growing seasons, and in one tree in each of four orchards during a single growing season. The LWD measurements revealed substantial heterogeneity among sensor locations. In all data sets, the upper, eastern portion of the canopy had the longest mean daily LWD, and was the first site to form dew and the last to dry. The lower, western portion of the canopy averaged about 3 h less LWD per day than the top of the canopy, and was the last zone where dew formed and the first to dry off. On about 25% of nights when dew occurred in the top of the canopy, no dew formed in the lower, western canopy. Intracanopy variability of LWD was more pronounced when dew was the sole source of wetness than on days when rainfall occurred. Daily LWD in the upper, eastern portion of the canopy was slightly less than reference measurements made at a 0.7-m height over turfgrass located near the orchard. When LWD measurements from several canopy positions were input to the SBFS warning system, timing of occurrence of a fungicide-spray threshold varied by as much as 30 days among canopy positions. Under Iowa conditions, placement of an LWD sensor at an unobstructed site over turfgrass was a fairly accurate surrogate for the wettest part of the canopy. Therefore, such an extra-canopy LWD sensor might be substituted for a within-canopy sensor to enhance operational reliability of the SBFS warning system.

Sooty blotch and flyspeck (SBFS) fungi colonize the surface wax layer of the fruit of apple, pear, persimmon, banana, orange, papaya, and several other cultivated tree and vine crops. In addition to colonizing cultivated fruit crops, SBFS fungi also grow on the surfaces of stems, twigs, leaves, and fruit of a wide range of wild plants. The disease occurs worldwide in regions with moist growing seasons. SBFS is regarded as a serious disease by fruit growers and plant pathologists because it can cause substantial economic damage. The smudges and stipples of SBFS often result in downgrading of fruit from premium fresh-market grade to processing use. This review describes the major shifts that have occurred during the past decade in understanding the genetic diversity of the SBFS complex, clarifying its biogeography and environmental biology, and developing improved management strategies.

Bacterial wilt, caused by Erwinia tracheiphila, is a major disease of cucurbit crops in the United States. Management of the disease relies on controlling two vector species, striped (Acalymma vittatum) and spotted (Diabrotica undecimpunctata) cucumber beetles. Six field trials were conducted at Iowa State University research farms during 2007, 2008, and 2009 to assess the efficacy of delayed removal of spunbond polypropylene row covers to control bacterial wilt on muskmelon (Cucumis melo). Treatments were (i) row cover removed at anthesis (conventional timing of removal), (ii) covers removed 10 days after row cover ends were opened at anthesis, (iii) covers removed 10 days after bumble bee hives were inserted under row covers at anthesis, and (iv) a noncovered control. In two field trials during 2007 and 2008, the delayed-removal row-cover treatments significantly suppressed bacterial wilt throughout the growing season and enhanced yield compared with the noncovered and removal-at-anthesis controls. In Gilbert in 2008, however, bacterial wilt suppression was equivalent among all three row-cover treatments. No bacterial wilt was observed during three trials in 2009, and there was minimal difference in marketable yield among treatments. Net returns were compared using partial budget and sensitivity analyses. Melon prices and occurrence of bacterial wilt had a strong impact on net returns. Using row covers increased production costs by 45%. In site years in which bacterial wilt occurred, delaying removal of row covers resulted in the highest returns. When bacterial wilt was absent, however, the delayed-removal row-cover treatments had the lowest returns. Results of the sensitivity analysis indicated that delaying removal of row covers for 10 days could be a cost-effective component of an integrated bacterial wilt suppression strategy for muskmelon where bacterial wilt occurs ≥50% of production seasons.

Bacterial wilt threatens cucurbit crop production in the Midwestern and Northeastern United States. The pathogen, Erwinia tracheiphila, is a xylem-limited bacterium that affects most commercially important cucurbit species, including muskmelon, cucumber, and squash. Bacterial wilt is transmitted and overwintered by striped and spotted cucumber beetles. Since there are few commercially available resistant cultivars, disease management usually relies on use of insecticides to suppress vector populations. Although bacterial wilt was initially described more than 100 years ago, our knowledge of disease ecology and epidemiology advanced slowly for most of the 20th century. However, a recent wave of research has begun to fill in missing pieces of the bacterial wilt puzzle. This article—the first review of research toward understanding the cucurbit bacterial wilt pathosystem—recounts early findings and updates our understanding of the disease cycle, including pathogen and vector biology. We also highlight research areas that could lead to more efficient and ecologically based management of bacterial wilt.

Colletotrichum acutatum, one of the most economically damaging pathogens of strawberry, is the primary causal agent of anthracnose fruit rot (AFR). A key challenge in managing AFR is detecting the pathogen on asymptomatic plants. To meet this need, a loop-mediated isothermal amplification (LAMP) assay was developed that incorporated two sets of primers: LITSG1, targeted on the intergenic transcribed spacer (ITS) region of ribosomal DNA, and Ltub2, on the β-tubulin 2 gene. In pure culture assays, Ltub2 was specific for detection of C. acutatum, whereas LITSG1 detected C. acutatum and two additional anthracnose pathogens, C. gloeosporioides and C. fragariae. LITSG1 had 10-fold lower detection threshold (20 pg of mycelial DNA) than Ltub2 (200 pg mycelial DNA) in detection of C. acutatum from pure culture. For detection on asymptomatic leaves, two protocols for dislodging C. acutatum for DNA extraction were compared: i) the sonicate-agitate (SA) method and ii) the freeze-incubate-sonicate-agitate (FISA) method, which initially freezes tissues, followed by 2 days of incubation at 26°C in darkness, and then, sonication and agitation. Both methods were used for greenhouse-grown plant leaves that had been spray inoculated with serial dilutions ranging from 1.5 × 106 to 1.5 conidia ml−1. The FISA method produced more repeatable results than the SA method. For the FISA method, detection limits (expressed as initial inoculum concentrations) using LITSG1 and Ltub2 were 1.5 × 101 and 1.5 × 102 conidia ml−1, respectively. For composite samples comprised of inoculated (1.5 × 106 conidia ml−1) and noninoculated leaves of greenhouse-grown strawberry, the two sets of LAMP primers were compared using the SA method. Primer set LITSG1 consistently detected the pathogen from a single inoculated leaf in bulk samples of 50 or fewer pathogen-free leaves, whereas Ltub2 consistently detected one inoculated leaf in 20 or fewer pathogen-free leaves. Using primer set LITSG1, FISA was more sensitive than SA for detecting C. acutatum on leaves of field-grown plants from Florida. In an Iowa field trial using the FISA method, both primer sets detected C. acutatum in samples of asymptomatic leaves 6 days before fruit symptoms appeared. The results indicate that the LAMP assay has potential to provide a simplified method for detection of C. acutatum on asymptomatic strawberry plants.

Sooty blotch and flyspeck (SBFS) is a fungal disease complex that can cause significant economic losses to apple growers by blemishing the fruit surface with dark-colored colonies. Little is known about the phenology of host infection for this diverse group of epiphytes. In 2009 and 2010, we investigated the timing of infection of apple fruit by SBFS species in six commercial apple orchards in Iowa. Five trees in each orchard received no fungicide sprays after fruit set. Within 3 weeks after fruit set, 60 apples per tree were covered with Japanese fruit bags to minimize inoculum deposition. Subsequently, a subsample of bagged apples was exposed for a single 2-week-long period and then rebagged for the remainder of the growing season. Experimental treatments included seven consecutive 2-week-long exposure periods; control treatments were apples that were either bagged or exposed for the entire season. After apples had been stored at 2°C for 6 weeks following harvest, all SBFS colonies on the apples were identified to species using a PCR-RFLP protocol. A total of 15 species were identified. For the seven most prevalent species, the number of infections per cm2 of fruit surface was greatest on apples that had been exposed early in the season. Two SBFS species, Peltaster fructicola and Colletogloeopsis-like FG2, differed significantly from each other in time required to attain 50% of the total number of colonies per apple, and analysis of variance indicated a significant interaction of SBFS taxon with exposure period. Our findings are the first evidence of species-specific patterns in timing of SBFS inoculum deposition and infection on apple fruit, and strengthen previous observations that most SBFS infections resulting in visible colonies at harvest develop from infections that occur early in the fruit development period. By defining taxon-specific phenological patterns of fruit infection, our findings, when combined with knowledge of region-specific patterns of taxon prevalence, provide a foundation for development of more efficient and cost-effective SBFS management tactics.

Early season brown spot caused by Septoria glycines was compared in Illinois, Indiana, Iowa, Michigan, and Ontario, Canada, soybean fields planted with differing commercial seed treatments. Seed treatments that included fluopyram significantly reduced brown spot (P < 0.001). A greenhouse mist chamber experiment revealed that fluopyram seed treatment reduced the Area Under Disease Progress Curve of brown spot over a 6-week period (P < 0.001). Brown spot severity was unaffected by plant age at inoculation for the control treatment without fluopyram (P = 0.911); however, severity increased with plant age at inoculation for the fluopyram treatment (P = 0.009). The sensitivity of two S. glycines isolates to fluopyram was assessed by determining the effective concentration required to reduce its colony diameter growth in culture by 50% (EC50). Both isolates had an EC50 of 0.41 μg/ml of fluopyram. These results demonstrate that fluopyram seed treatment is effecttive at controlling early season brown spot in soybean. Accepted for publication 19 September 2016.

Field validation of a disease-warning system for strawberry anthracnose fruit rot (AFR), caused by Colletotrichum acutatum sensu lato, that was originally developed for use in Florida was conducted in Iowa from 2012 to 2014. Day-neutral strawberry (cv. Tristar) was artificially inoculated with the pathogen at the start of the fruit maturation period. A factorial combination in replicated trials of two spray timing methods (the Florida warning system and prescheduled, calendar-based timing) and two fungicides (captan and pyraclostrobin) was compared, along with a nonsprayed control. The calendar-based and warning system-based treatments provided statistically equivalent control of AFR incidence compared with the nonsprayed control, and the warning system treatments required an average of 1.7 fewer fungicide sprays annually than the calendar-based treatments. Further analysis of the field data suggested that the warning system might underestimate AFR risk under high disease pressure; in these circumstances, a lower action threshold value may need to be adopted. Overall, these results indicated that the Florida warning system can be valuable for helping Midwest strawberry growers control AFR with less reliance on fungicide sprays, but it may require modification to account for periods of high inoculum pressure, subject to results of further field trials.

Plastic mulch is often used in cucurbit production, but it has negative soil health and environmental implications due to use of tillage for installation and generation of plastic waste. This 2-year study aimed to find a viable alternative to plastic mulch through the use of strip tillage and rowcovers, as rowcovers could help minimize yield loss from strip tillage by providing warmer air and soil as well as providing insect protection. A split-plot design was used in both conventionally and organically managed summer squash (Cucurbita pepo), with production system as the whole-plot factor [conventional tillage with black plastic mulch also referred to as plasticulture (PL) and strip tillage into rolled cereal rye (Secale cereale) (ST)] and rowcover use as the subplot factor (rowcover until anthesis or no rowcover). Rowcovers reduced the incidence of squash vine borer (Melittia cucurbitae) and eliminated the need for insecticide sprays to control this insect pest, but did not reduce the incidence of yellow vine decline or the sprays needed to control squash bug (Anasa tristis). Rowcovers increased average air temperature by 1.6 to 4.0 °C and increased maximum air temperature by up to 10.3 °C. Rowcovers decreased average light intensity by 33% to 39%. Though soil temperature in PL tended to be higher than in ST, in 1-year rowcovers helped bridge the gap. Plant biomass was consistently higher in the PL than the ST system. Averaged across rowcover treatments, plants in PL had higher marketable yields than those in ST; however, the use of rowcovers often led to comparable yields between the production system treatments. Rowcover was a significant factor explaining marketable yield for the organically managed fields both years. There was no consistent effect of production system on soil microbial biomass carbon (MBC). Based on our results, strip tillage into rolled rye could be a viable alternative to plasticulture for summer squash production in Iowa, and rowcovers could help increase yields in ST especially in an organic management system.

The goal of this study was to develop a systems-based strategy for organic muskmelon (Cucumis melo var. reticulatus) in Pennsylvania (PA), Iowa (IA), and Kentucky (KY) to manage bacterial wilt (Erwinia tracheiphila) and nutrients while safeguarding yield and enhancing early harvest. Spunbond polypropylene rowcovers deployed for different timings during the growing season were evaluated for suppressing bacterial wilt and locally available compost was applied based on two different estimated rates of mineralization of organic nitrogen (N) to manage nutrients. In KY only, the use of rowcovers suppressed bacterial wilt incidence compared with not using rowcovers. However, the timing of rowcover removal did not impact wilt incidence. Under lower cucumber beetle [striped cucumber beetle (Acalymma vittatum) and spotted cucumber beetle (Diabrotica undecimpunctata howardi)] pressure in PA and IA, rowcovers did not consistently suppress season-long incidence of bacterial wilt. In four of five site-years in PA and IA, more marketable fruit were produced when rowcovers were removed 10 days after an action threshold (the date the first flower opened in PA; the date when ≥50% of plants in a subplot had developed perfect flowers in IA and KY) than when no 10-day delay was made or when no rowcovers were used. In addition, the no-rowcover treatment consistently had lower weight per marketable fruit. In KY, the same action threshold without the 10-day delay, followed by insecticide applications, resulted in the largest number of marketable fruit, but did not affect marketable fruit weight. In PA, marketable yield was higher using compost compared with the organic fertilizer in 1 year. No yield differences were observed by nutrient treatments in 2 years. In IA, marketable yield was lower with the low amount of compost compared with the organic fertilizer and yields with the high amount of compost were not different from the low amount or the organic fertilizer in the year it was evaluated. In KY, marketable yield was unaffected by the nutrient treatments in the year it was evaluated. Given these results, muskmelon growers in PA, IA, and KY who use compost may choose the lower compost rate to minimize production costs. Overall, these findings suggest that rowcover-based strategies for organic management of bacterial wilt need to be optimized on a regional basis, and that fertilization with compost is compatible with these strategies.

Increasing interest in using cover crops and reduced tillage to build soil health has created a demand for strategies to implement rolled cover crop systems. In northern areas of the United States, cool soil temperature in rolled cover crop systems can create a challenge when growing warm season vegetable crops. The use of rowcovers could mitigate the issue and facilitate adoption of rolled cover crop systems for both conventional and organic growers. This study investigated muskmelon (Cucumis melo) in two production systems, strip tillage (ST) into rolled cereal rye (Secale cereale) or conventional tillage with black plastic mulch (plasticulture), with or without the use of spunbonded polypropylene rowcovers. The trial was conducted in two fields, one in organic management and the other in conventional management. In general, ST led to cooler, moister soils than plasticulture, but rowcovers rarely affected soil temperature. Rowcovers increased mean and maximum daily air temperature by up to 4.2 and 11.7 °C, respectively, and decreased average daily light intensity by 33% to 37%. Rowcovers sometimes increased fruit size, but rarely affected marketable yield. Overall, ST reduced marketable yield compared with plasticulture by 6732 to 9900 lb/acre; however, ST with rowcovers often produced similar vegetative growth compared with plasticulture without rowcovers. Given the slow vining growth habit of muskmelon and the late planting inherent in a rolled cereal rye system, achieving high muskmelon yields, especially early yields, may be difficult.

Sooty blotch and flyspeck (SBFS) is a complex of at least 80 fungal species in 24 genera within the Dothideomycetes order Capnodiales. These epiphytes embed in the waxy epicuticle of apple fruit and colonies become visible in mid- to late summer. The blemished fruit are not marketable as fresh produce. Previous surveys of orchards in central and eastern USA and southern Europe found SBFS assemblages that were unique to geographic region. In the USA, SBFS species diversity was higher in orchards that received no fungicide sprays than those receiving fungicide sprays, suggesting that orchard management was an important determinant of SBFS species distribution and prevalence. To test the hypothesis that the composition of the SBFS complex is affected by geographic region and orchard management practices in Norway, 35 sites with a range of different management practices and cultivars were sampled. Colonies on each apple were counted according to the mycelial type, and subsamples of each mycelial type were amplified and sequenced using either primers specific to the rDNA of Capnodiales or a universal fungal primer pair for the large subunit of rDNA. Results indicated that a single genus was associated with each mycelial type. Seven genera known to cause SBFS were identified: Microcyclospora, Dissoconium, Peltaster, Microcyclosporella, Phaeothecoidiella, Schizothyrium, and Geastrumia. The percent composition of each site’s SBFS assemblage was estimated to genus. Significant differences were found in SBFS assemblages among geographic districts and management practices, and there was a significant interaction of district and management. Organic orchards tended to have the least SBFS severity and genus diversity, whereas higher SBFS diversity tended to occur in abandoned than managed orchards. This is the first survey of SBFS fungi in apple orchards in Scandinavia.

Sooty blotch and flyspeck is a fungal disease complex that colonizes a wide range of plants. In a survey of host plants for sooty blotch and flyspeck fungi, we obtained an isolate associated with discrete flyspeck symptom on stems of the Rubber Trees, Ficus elastica, from Haikou, Hainan, China. A pure culture was obtained, and the nuclear ITS region of rDNA was amplified by PCR. Molecular phylogeny inferred from ITS sequence data suggested that it was close to Devriesia strelitziae, reported from South Africa. Morphologically, it was characterized by longer conidia, more conidial septa, and having chlamydospores. Therefore, we describe our isolate as a novel species of Devriesia.

Members of the sooty blotch and flyspeck (SBFS) complex are epiphytic fungi in the Ascomycota that cause economically damaging blemishes of apples worldwide. SBFS fungi are polyphyletic, but approx. 96% of SBFS species are in the Capnodiales. Evolutionary origins of SBFS fungi remain unclear, so we attempted to infer their origins by means of ancestral state reconstruction on a phylogenetic tree built utilizing genes for the nuc 28S rDNA (approx. 830 bp from near the 59 end) and the second largest subunit of RNA polymerase II (RPB2). The analyzed taxa included the well-known genera of SBFS as well as non-SBFS fungi from seven families within the Capnodiales. The non-SBFS taxa were selected based on their distinct ecological niches, including plant-parasitic and saprophytic species. The phylogenetic analyses revealed that most SBFS species in the Capnodiales are closely related to plant-parasitic fungi. Ancestral state reconstruction provided strong evidence that plant-parasitic fungi were the ancestors of the major SBFS lineages. Knowledge gained from this study may help to better understand the ecology and evolution of epiphytic fungi.

Sooty blotch and flyspeck (SBFS) is a complex of more than 80 fungal species in 24 genera, mostly belonging to the order Capnodiales within the Dothideomycetes. Colonies of these epiphytes become visible on the surface of apples in mid- to late summer. Several species of SBFS fungi have been previously identified from apples in Germany, but little is known about species diversity, prevalence patterns, or relationship to orchard management practices. To address these questions, apple orchards were surveyed during the 2008 to 2011 seasons in the two largest German apple-growing regions along the Lower Elbe river (northern Germany) and Lake Constance (southern Germany). Using a combination of approaches based on morphology and ITS sequence data, 19 known or putative SBFS species were found, of which 10 belonged to Capnodiales. Abandoned orchards harboured a higher species diversity than organically managed orchards, and no SBFS disease was seen in orchards under integrated pest management. Peltaster cerophilus was the most common SBFS fungus, being associated with 96 and 84 % of SBFS-affected apples sampled from northern and southern German organic orchards, respectively. Microcyclosporella mali and Cyphellophora sessilis were the next most commonly found SBFS species in northern and southern Germany, respectively. Schizothyrium pomi was the only cause of the flyspeck mycelial type of SBFS disease in Germany.

Sooty blotch and flyspeck (SBFS) is a mid- to late-season fungal disease complex that blemishes apples and other tree fruit crops in humid regions worldwide. SBFS is a concern for apple growers in northeastern Turkey, but the composition of the SBFS species assemblage in Turkey is unknown. In this study, SBFS fungi were isolated from apples collected in 2008 in the Rize Province of northeastern Turkey. Pressed SBFS colonies with subtending apple cuticle were shipped to Iowa State University for isolation. Of 633 primary isolates from 148 apple peels, 87 cultures were purified, 67 isolates were genetically characterized and 33 isolates examined for morphology. The internal transcriber spacer (ITS) ribosomal DNA and a portion of the 28S large subunit region (LSU) were compared to previously identified fungi using parsimony analysis. Putative species were delineated from ITS sequences as well as morphology on apple and in culture. Twelve species were delineated based on parsimony analysis of ITS sequences and morphology. A newly discovered and described species from the survey was Scleroramularia abundans; newly discovered putative species included Zygophiala sp. FS3.3, Stomiopeltis spp. RS7.1 and RS7.2, and Chaetothyriales sp. F1; previously recovered putative species included Zygophiala sp. FS6 and Stomiopeltis sp. RS4.1; and previously discovered and named SBFS species included Schizothyrium pomi, Zygophiala wisconsinensis, Microcyclosporella mali, Microcyclospora tardicrescens, and Peltaster fructicola. Based on parsimony analysis of the LSU, one species was placed in the subclass Chaetothyriomycetidae and 11 species were placed in subclass Dothideomycetidae. Ten species were placed in the order Capnodiales. These findings expand the documented extent of genetic diversity within the worldwide SBFS complex and are the first published description of the composition of the SBFS complex from Turkey.

Sooty blotch and flyspeck (SBFS) is a complex of about 80 fungal species that blemish the surface of apple fruit in humid regions worldwide. The dark colonies become visible in mid- to late summer, reducing the value of fresh fruit. Although many SBFS species can co-occur in the same orchard and even on the same apple, little is known about temporal patterns of these species, including the timing of colony appearance. To test the hypothesis that colonies of SBFS species appear on apples at characteristic times during the growing season, 50 apples were monitored weekly at three Iowa orchards in 2006 and six orchards in 2007 and 2008. However, a mean of 24.3 apples per orchard was assessed at harvest because of apple drop throughout the season. Colonies were marked with colored pens as they appeared. After harvest and after storage of apples at 2 °C for 3 months, SBFS colonies on each fruit were counted and classified by morphology, and a representative subset of colonies was excised from the fruit and preserved on dried peels for species identification using rDNA. Seventeen species were identified. Stomiopeltis spp. RS1 and RS2 appeared on apples 10 to 14 days before other SBFS taxa. Dissoconium aciculare was generally the last species to appear on apple fruit, and it continued to appear during postharvest storage. The most prevalent taxa in Iowa orchards were also the most abundant. Diversity of SBFS fungi in an orchard was positively correlated with cumulative hours of surface wetness hours due to rainfall or dew, which is believed to favor growth of SBFS fungi. Species-specific information about temporal patterns of appearance on apple fruit may lead to improved SBFS management strategies.

Zasmidium angulare, a novel species of Mycosphaerellaceae, and several novel taxa that reside in Dissoconiaceae, were identified from a collection of apples and Cucurbita maxima (cv. Blue Hubbard) from China and the USA that exhibited sooty blotch and flyspeck (SBFS) signs on their host substrata. Morphology on fruit surfaces and in culture, and phylogenetic analyses of the nuclear ribosomal DNAs 28S and internal transcribed spacer regions, as well as partial translation elongation factor 1-alpha gene sequences in some cases, were used to delineate seven previously unidentified species and three known species. Pseudoveronaea was established as a new genus of Dissoconiaceae, represented by two species, P. ellipsoidea and P. obclavata. Although Pseudoveronaea was morphologically similar to Veronaea, these fungi clustered with Dissoconiaceae (Capnodiales) rather than Chaetothyriales (Herpotrichiellaceae). Ramichloridium mali comb. nov., and three novel species, R. cucurbitae, R. luteum and R. punctatum were closely related with R. apiculatum, which together formed a distinct subclade in Dissoconiaceae. Species of Dissoconium s.lat. clustered in two well-supported clades supported by distinct morphological and cultural features. Subsequently Uwebraunia, a former synonym of Dissoconium, was resurrected for the one clade, with new combinations proposed for U. australiensis, U. commune, U. dekkeri and U. musae. Furthermore, we also reported that D. aciculare, Dissoconium sp., U. commune and U. dekkeri were associated with SBFS on apples.

Sooty blotch and flyspeck is caused by numerous species of fungi that colonize the surface of apple fruit and thereby lower its market value. Although this disease poses a substantial threat to apple growers’ profitability in some regions, reliable and cost-effective methods for epidemiological and disease control studies have not been validated, nor are they widely available. We modified a standard area diagram to aid sooty blotch and flyspeck severity assessments and quantified its impact on accuracy and precision of visual estimates. Samples of ‘Fuji’ and ‘Mutsu’ fruit were photographed both from the top and laterally. Severity was assessed from a sub-sample of 160 images using image analysis software. Validation of the diagram was performed by eight raters who independently assessed severity in two series of selected images representing the lateral view and the top view, initially unaided and subsequently with the aid of the scale. Severity estimates ranged from 0.4% to 98% (most fruit had

Zygophiala qianensis is described as a new fungal species associated with the cuticle of apple fruit sampled from an orchard in Shaanxi Province, China. Conidiophores were separate, arising from superficial hyphae, erect, scattered, subcylindrical, irregularly flexuous, consisting of four parts: a hyaline supporting cell that gives rise to a smooth, dark brown stipe, terminating in a finely verruculose, medium brown apical cell that gives rise to (1–)2(–3) medium brown, finely verruculose, doliiform to ellipsoidal, polyblastic conidiogenous cells, with 1–2 prominent scars, apical and lateral, darkened, thickened. Conidia were solitary, fusiform to obclavate, hyaline, smooth and thick-walled, transversely (0–)1(–7)-septate, mostly 1–2-septate, prominently constricted at the septum; apex obtuse, base subtruncate, with a darkened, thickened hilum. Zygophiala qianensis is compared morphologically to other species of Zygophiala, and a phylogenetic analysis of their DNA sequence data is presented.

Up to now, four species of Zygophiala have been recorded, most of them as agents of flyspeck disease on apples. Two species of Zygophiala associated with flyspeck on apple in China are described in this paper. Zygophiala cylindrica is described as a new fungal species based on morphological characteristics and analysis of DNA sequences, and a phylogenetic analysis of the DNA sequences data is presented. Zygophiala cryptogama is recorded for the first time in China.

Disease-warning systems are decision support tools designed to help growers determine when to apply control measures to suppress crop diseases. Weather data are nearly ubiquitous inputs to warning systems. This contribution reviews ways in which weather data are gathered for use as inputs to disease-warning systems, and the associated logistical challenges. Grower-operated weather monitoring is contrasted with obtaining data from networks of weather stations, and the advantages and disadvantages of measuring vs. estimating weather data are discussed. Special emphasis is given to leaf wetness duration (LWD), not only because LWD data are inputs to many disease-warning systems but also because accurate data are uniquely challenging to obtain. It is concluded that there is no single " best" method to acquire weather data for use in disease-warning systems; instead, local, regional, and national circumstances are likely to influence which strategy is most successful.

A restriction fragment length polymorphism (RFLP)-based technique was developed to identify members of the sooty blotch and flyspeck (SBFS) disease complex on apple because these fungi are difficult to identify using agar-plate isolation and morphological description. The method includes polymerase chain reaction (PCR) amplification of the internal transcribed spacer (ITS) region of ribosomal DNA (rDNA) using a fungal-specific forward primer (ITS1-F) and an SBFS-specific reverse primer (Myc1-R), followed by digestion of the PCR product by the HaeIII restriction enzyme. When applied to previously identified isolates of 24 SBFS-causing species in nine genera, the PCR-RFLP assay produced 14 unique banding patterns. Different genera never shared the same RFLP pattern. To evaluate performance in vivo, the technique was applied to DNA extracted directly from SBFS colonies on apple fruit from three Iowa orchards. The primers amplified the rDNA of only SBFS fungi, with the exception of a Cladosporium sp.; however, its RFLP banding pattern was distinct from those of SBFS fungi. The majority (60%) of SBFS colonies in the in vivo trial were identified to genus by RFLP analysis. The PCR-RFLP assay greatly streamlined the identification process by minimizing the need for culturing, indicating its value as a tool for field studies of the SBFS complex.

Sooty blotch and flyspeck (SBFS) is a late-season disease of apple and pear fruit that cosmetically damages the cuticle, resulting in produce that is unacceptable to consumers. Previous studies reported that four species of fungi comprise the SBFS complex. We examined fungal morphology and the internal transcriber spacer (ITS) and large subunit (LSU) regions of rDNA of 422 fungal isolates within the SBFS complex from nine orchards in four Midwestern states (USA) and compared them to previously identified species. We used LSU sequences to phylogenetically place the isolates at the order or genus level and then used ITS sequences to identify lineages that could be species. We used mycelial and conidial morphology on apple and in culture to delimit putative species. Thirty putative species found among the Midwest samples were shown to cause SBFS lesions on apple fruit in inoculation field trials. Among them Peltaster fructicola and Zygophiala jamaicensis have been associated previously with SBFS in North Carolina. The LSU analyses inferred that all 30 SBFS fungi from Midwestern orchards were Dothideomycetes; one putative species was within the Pleosporales, 27 were within Dothideales, and two putative species could not be placed at the ordinal level. The LSU sequences of 17 Dothideales species clustered with LSU sequences of known species of Mycosphaerella.

Adopting the currently used concept for the genus Peltaster, the sooty blotch fungus Peltaster cerophilus is newly described from the cuticle of ripening or ripe apples. It forms a punctate phenotype consisting of superficially formed pycnothyria and a superficial mycelial mat consisting of a net of brown or brownish black hyphae. The pycnothyria are olivaceous brown to brown but have a spot in the center that is less strongly pigmented. Pycnothyria on the holotype of P. fructicola are homogeneously pigmented. On synthetic nutrient-poor agar, P. cerophilus is largely indistinguishable from P. fructicola. It forms delicate, spreading hyphae and intercalary conidiogenous cells with short, lateral, apically thick-walled conidiogenous necks forming blastic, unpigmented, one-celled conidia in basipetal succession. Conidia can swell and become one-septate. The species has microcyclical conidiation in proximate parts of colonies. DNA sequence analyses based on the ITS and the partial nuclear small and large subunit ribosomal RNA genes, the partial mitochondrial small subunit rRNA gene and the partial translation elongation factor 1-α gene support the distinction of the European P. cerophilus from P. fructicola, which is known from North America and Europe. The nuclear small ribosomal RNA subunit gene sequences of P. cerophilus contain two group I introns at locations known to accommodate introns in certain other, unrelated taxa. One of these, for which the code "SSU-1506 intron" was adopted, is 1459 base pairs long and located between the universal primer sites ITS5 and ITS1. Similar or positional-differing introns were encountered also in three currently undescribed Peltaster species. Representative strains of Peltaster fructicola did not accommodate introns in the nuclear small subunit ribosomal RNA gene.

Beneficial insects can provide valuable ecosystem services such as pest control and pollination for agricultural crops, but agricultural crops often provide limited food and refuge resources necessary to these beneficial insects. Planting flowers can provide some of these limited resources such as nectar, pollen, and refuge. Floral provisioning could enhance the beneficial insect community in agricultural crops if flowers are placed adjacent to the crops. This research project explores whether floral provisioning can increase the ecosystem services provided by pollinating and predatory insects in agricultural crops.

Species in the genus Zygophiala are associated with sooty blotch and flyspeck disease on a wide range of hosts. In this study, 63 Zygophiala isolates collected from flyspeck colonies on a range of plants from several regions of China were used for phylogeny, host range and geographic distribution analysis. Phylogenetic trees were constructed on four genes - internal transcribed spacer (ITS), partial translation elongation factor 1-alpha (TEF), β-tubulin (TUB2), and actin (ACT) – both individually and in combination. Isolates were grouped into 11 clades among which five new species, Z. emperorae, Z. trispora, Z. musae, Z. inaequalis and Z. longispora, were described. Species of Zygophiala differed in observed host range and geographic distribution. Z. wisconsinensis and Z. emperorae were the most prevalent throughout the sampled regions of China, whereas Z. trispora, Z. musae, Z. inaequalis and Z. longispora were collected only in southern China. The hosts of Z. wisconsinensis and Z. emperorae were mainly in the family Rosaceae whereas Z. trispora, Z. musae, Z. inaequalis and Z. longispora were found mainly on banana (Musa spp.). Cross inoculation tests provided evidence of host specificity among SBFS species.

Introduction Anthracnose fruit rot (AFR) of strawberry is caused by three Colletotrichum spp. In the Midwest, however, only Colletotrichum acutatum is found. This fungus can attach itself to apparently healthy plants and spread throughout the field without causing symptoms on the foliage. When fruit begins to ripen and weather conditions are rainy and warm, AFR can suddenly cause great damage to the fruit. To protect against AFR where it has appeared in the past, growers need to spray every 7 to 10 days beginning at the start of bloom until harvest.

Five cultivars of Fraxinus americana (white ash) and five of F. pennsylvanica (green ash) were graft-inoculated with three strains of ash yellows phytoplasmas at Ames, IA, and with thrsee other strains at Ithaca, NY. A sixth green ash cultivar was tested only in New York. Trees were allowed to grow in field plots for 3 years. Infection was detected via the DAPI (4′, 6-diamidino-2-phenylindole 2HCl) fluorescence test. Incidence of witches'-brooms on infected trees was greater on white ash than green ash and varied significantly among phytoplasma strain treatments at both locations. Volume growth of infected ash, averaged across cultivars over 2 years in Iowa and 3 years in New York, was 49 and 59%, respectively, as great as that of noninfected trees. Foliar greenness was reduced significantly by infection at both locations, and this reduction was positively correlated with growth reduction. Cultivars at each location varied significantly in growth of noninfected trees and in growth of diseased trees relative to that of nonin-fected trees (a measure of phytoplasma tolerance), but cultivar means for these variables in Iowa were not significantly correlated with those in New York. Green ash cvs. Bergeson, Dakota Centennial, and Patmore and white ash cv. Autumn Applause were above average in tolerance at both locations. Phytoplasma strains at each location varied significantly in aggressiveness as indicated by host growth suppression.

The causal agent of cucurbit bacterial wilt, Erwinia tracheiphila, has a wide host range in the family Cucurbitaceae, including economically important crops such as muskmelon (Cucumis melo), cucumber (C. sativus), and squash (Cucurbita spp.). Genetic variability of 69 E. tracheiphila strains was investigated by repetitive-element polymerase chain reaction (rep-PCR) using BOXA1R and ERIC1-2 primers. Fingerprint profiles revealed significant variability associated with crop host; strains isolated from Cucumis spp. were clearly distinguishable from Cucurbita spp.-isolated strains regardless of geographic origin. Twelve E. tracheiphila strains isolated from muskmelon, cucumber, or summer squash were inoculated onto muskmelon and summer squash seedlings, followed by incubation in a growth chamber. Wilt symptoms were assessed over 3 weeks, strains were reisolated, and rep-PCR profiles were compared with the inoculated strains. Wilting occurred significantly faster when seedlings were inoculated with strains that originated from the same crop host genus (P