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Verticillium wilt, caused by Verticillium dahliae , is one of the major diseases of eggplants. Nanoparticles (NPs) of CuO, Mn 2 O 3 , and ZnO were sprayed alone onto leaves of young eggplants and in different combinations and rates, and then seedlings were transplanted into soil infested with V. dahliae in the greenhouse and field between 2015 and 2018. All combinations of NPs were consistently less effective than CuO NPs applied alone at 500 µg/ml at increasing disease suppression, biomass, and fruit yield. CuO NPs were associated with an increase in fruit yield (17 and 33% increase) and disease suppression (28 and 22% reduction) in 2016 and 2017, respectively, when compared with untreated controls. However, this effect was negated in the greenhouse and field experiments when CuO NPs were combined with Mn 2 O 3 . Combining NPs of CuO with ZnO resulted in variable effects; amendments increased growth and suppressed disease in greenhouse experiments, but results were mixed in the field. Leaf tissue analyses from the greenhouse experiments showed that Cu concentration in leaves was reduced when CuO NPs were combined with other NPs, even when application rates were the same amount. A simple competition for entry sites may explain why combinations of CuO NPs and Mn 2 O 3 NPs reduced efficacy but does not explain the lack of inhibition between Cu and Zn. NPs of CuO performed better than their larger bulk equivalent, and studies on application rate found 500 µg/ml was optimal. No phytotoxicity, as determined, by leaf burning, necrotic spots, or dead apical buds was noted even at the highest combined rates of 1,500 µg/ml.

Asparagus can suffer from a crown and root rot caused by Fusarium oxysporum f. sp. asparagi and F. proliferatum. The disease is exacerbated when allelopathic toxins from old, rotting asparagus crowns are present in the soil. To minimize the damage from the replant problem, three strategies were examined: (i) biochar, (ii) application of earthworms (Lumbricus terrestris), and (iii) leaf mold to serve as a compost mulch and food source for earthworms. In a greenhouse, asparagus transplants were grown in soil amended with pathogen-infested asparagus residues or in nonamended soil, then both types of soil were augmented with biochar, earthworms, the combination of biochar and earthworms, or no treatment. Biochar increased arbuscular mycorrhizae (AM) colonization by 170% and reduced the incidence of root lesions by 57%; however, plant weight was not affected by any of the soil treatments and there were no significant interactions among the main effects. In the absence of infested asparagus residues, biochar reduced plant growth by 32%. Field plots that had severe crown and root rot, along with two other fields that had never been planted to asparagus, were planted with asparagus crowns and treated with leaf mold mulch, earthworms plus leaf mold mulch, biochar, or biochar plus earthworms plus leaf mold mulch. Untreated plots served as the control treatment. One year later, asparagus roots sampled from plots in the two new fields had a threefold increase in AM colonization when treated with biochar compared with control plots. Biochar did not increase yield over the duration of the 2012 to 2014 harvests when compared with that of the control plots. No soil treatment affected root colonization by AM in the field where Fusarium crown and root rot was severe. Compared with the untreated control plots, the leaf mold mulch treatment applied alone increased the marketable yields in each year of harvest. Combining leaf mold with earthworms provided no added benefit. Soil amendment with leaf mulch alone may hold promise for improving asparagus production in newly planted asparagus fields.

Salt marshes rank as the most productive ecosystems on the planet. Biomass production can be greater than 3 kg dry matter/m 2 /year, which is 40% more biomass than tropical rainforests produce. Salt marshes provide multiple benefits to mankind. For example, coastal communities receive protection from storm surges and wave erosion. Salt marshes absorb excess nitrogen and phosphorus from sewage and fertilizer run-off into rivers, which, in turn, prevents algal blooms and hypoxia in coastal waters. In addition, these unique ecosystems provide habitat and shelter for many hundreds of species of shellfish, finfish, migratory and sedentary birds, and other marine animals. Despite the richness in animal species, the intertidal marshes of the salt marsh ecosystem are dominated by only a few plant species. Of these, the most prevalent plant species in a marsh are the tall and short forms of smooth cordgrass (Spartina alterniflora). The first recorded account of a dieback in a U.S. salt marsh was in the early 1990s in the Florida panhandle where patches of Sp. alterniflora as large as 1 ha died. This article explores possible causes of Sudden Vegetation Dieback.

The epidemiology and strategies for management of Fusarium wilt of China aster (Callistephus chinensis) were studied in Connecticut and Florida, USA, by examining seed contamination, on-farm disease incidence, sanitation, host resistance, and various soil treatments. Five out of 25 commercial seed packages from three separate distribution companies assayed in Connecticut had seeds contaminated with the pathogen Fusarium oxysporum f. sp. callistephi. Farm surveys of two cut-flower farms in Connecticut had disease incidences of 32 and 58%, while in Florida, the incidence of the disease ranged from 0.002 to 71.2% in two cut-flower operations. All pathogenic isolates from seed and symptomatic plants in Connecticut were vegetatively compatible, suggesting a common origin. Pathogenic isolates from Florida and nonpathogenic isolates fell into different vegetative compatibility groups and may have had another origin. Sodium hypochlorite solutions (1%) eliminated the fungus from seeds and Styrofoam when applied as a soak or spray, respectively. Soil fumigation with methyl bromide + chloropicrin, 1,3-dichloropropene + chloropicrin, or metam sodium maintained Fusarium wilt at low levels at a Florida cut-flower production facility. Evaluations of disease resistance of 44 cultivars in the greenhouse identified eight cultivars with moderate resistance. Four cultivars were identified with moderate resistance in field trials and thus could serve as a source of resistant germplasm for future breeding programs. These findings should encourage growers to use sanitation protocols to prevent entry of the pathogen into their fields and to choose commercially available cultivars that have moderate resistance.

Bloodroot (Sanguinaria canadensis L [Papaveraceae]) is a native herbaceous perennial in eastern North America, found from Nova Scotia to Florida. Although it is a common wildflower, rhizomes of double-flowered forms are sold commercially. Rhizomes planted into a wooded area in Guilford, CT produced healthy stems and flowers for a few years and then began to collapse and die in 2008. The same symptoms were observed with a new planting in 2011. Initially, leaves were dull green and were more leathery than healthy leaves. Eventually, the leaves collapsed at the junction of the petioles and the rhizomes. Vascular discoloration, if present, was obscured by the red pigmentation in the rhizome. A Fusarium sp. sporulated on the discolored tissue at the junction between healthy and rotted tissue. Stem pieces were surface disinfested (0.53% NaClO for 1 min), rinsed, and placed on Peptone-PCNB agar (2) at room temperature for 5 days. Colonies originating from single spores were subcultured on carnation leaf agar (2) and identified as Fusarium oxysporum based on falcate, thin-walled, three-septate macroconida borne in monophialides on doliform conidiophores (2). Four rhizomes of double-flowered bloodroot were planted in potting mix in the greenhouse in October 2010; sprouts were observed in March 2011. Two plants were inoculated in March 2011 by drenching the soil with 100 ml of a conidial suspension (10 6 spores/ml) and two control plants were treated with deionized water. Two months later, the inoculated plants were smaller than the controls. The treated plants subsequently collapsed and F. oxysporum was reisolated. Control plants remained healthy and F. oxysporum was not isolated. DNA extracted from the F. oxysporum isolates was used to obtain partial sequences of the translational elongation factor 1-alpha (tef1) gene, which were then blasted against the GenBank database. We observed a 100% similarity with F. oxysporum f. sp. lycopersici. The bloodroot isolates were compared with a known F. oxysporum f. sp. lycopersici isolate for their ability to cause disease on 2-week-old tomato seedlings (cv. Brandywine), using pathogenicity tests as described above. The known F. oxysporum f. sp. lycopersici isolate caused severe wilt and stunting of the tomato seedlings, but the bloodroot isolate caused no symptoms in inoculated seedling compared with those not inoculated. These results suggest that there may be more hosts for isolates in the F. oxysporum f. sp. lycopersici species complex than previously thought (1). An isolate (O-2603) has been deposited at the Fusarium Research Laboratory at Pennsylvania State University, University Park. Since bloodroot is now being sold commercially as an ornamental, disease management strategies may be needed. To our knowledge, this is the first report of a Fusarium crown rot of bloodroot. References: (1).V. Edel-Hermann et al. Online publication. doi:10.1111/j.1365-3059.2011.02551.x. Plant Pathology, 2011. (2) J. Leslie and B. Summerell. The Fusarium Laboratory Manual. Blackwell Publishing, Ames, IA, 2006.

Pyrolyzed biomass waste, commonly called biochar, has attracted interest as a soil amendment. A commercial prototype biochar produced by fast pyrolysis of hardwood dust was examined in soils to determine if it could reduce the damaging effect of allelopathy on arbuscular mycorrhizal (AM) root colonization and on Fusarium crown and root rot of asparagus. In greenhouse studies, biochar added at 1.5 and 3.0% (wt/wt) to asparagus field soil caused proportional increases in root weights and linear reductions in the percentage of root lesions caused by Fusarium oxysporum f. sp. asparagi and F. proliferatum compared with a control. Concomitant with these effects was a 100% increase in root colonization by AM fungi at the 3.0% rate. Addition of aromatic acids (cinnamic, coumaric, and ferulic) that are known allelopathic agents affecting asparagus reduced AM colonization but the deleterious effects were not observed following the application of biochar at the higher rate. When dried, ground, asparagus root and crown tissues infested with Fusarium spp. were added to soilless potting mix at 0, 1, or 5 g/liter of potting mix and then planted with asparagus, there was a decrease in asparagus root weight and increase in disease at 1 g/liter of potting mix but results were inconsistent at the higher residue rate. However, when biochar was added at 35 g/liter of potting mix (roughly 10%, vol/vol), these adverse effects on root weight and disease were equal to the nontreated controls. A small demonstration was conducted in field microplots. Those plots amended with biochar (3.5% [wt/wt] soil) produced asparagus plants with more AM colonization in the first year of growth but, in the subsequent year, biochar-treated plants were reduced in size, possibly due to greater than average precipitation and the ability of biochar to retain moisture that, in turn, may have created conditions conducive to root rot. These studies provide evidence that biochar may be useful in overcoming the deleterious effects of allelopathic residues in replant soils on asparagus.

The role of earthworms in plant disease has received little attention. To address whether earthworms would affect the severity of Verticillium wilt of eggplant (Solanum melongena) in the field, we grew eggplants in experimental field plots that were naturally infested with Verticillium dahliae in 2005, 2006, and 2007. Three earthworm treatments were compared: (i) no treatment (untreated control), (ii) earthworm populations reduced via chemical eradicants (carbaryl or hot mustard) (reduced treatment), and (iii) earthworm populations increased by addition of adult Canadian nightcrawlers (Lumbricus terrestris, 11 earthworms per m 2 ) (augmented treatment). Compared to the untreated control, the estimates of the area under the disease progress curve (AUDPC) were reduced while estimates of the canopy growth curve (CGC) and the final plant weights were increased in plots augmented with earthworms in all 3 years. In 2 out of 3 years, eggplant yield (weight and number of fruit) was increased in plots augmented with earthworms. When a carbaryl drench was used to reduce earthworm numbers, the treatment resulted in plants with more disease than in the untreated controls in 2005. However, in 2005 and 2006, carbaryl-treated plants had larger CGC values and higher yield than in the untreated controls and were not significantly different from the augmented plots. When a hot mustard extraction procedure was used to reduce earthworm densities in 2007, plant growth, yield, and disease variables did not differ from the untreated control. Although the effects of reducing earthworms were variable and difficult to explain, our findings suggest that augmenting earthworm populations can suppress Verticillium wilt of eggplant, and strategies that increase earthworm numbers may contribute to disease suppression.

Earthworm densities have been regarded as reliable indicators of soil health, but their role in suppression of plant disease has not received much attention. Several greenhouse studies were done to determine if soils infested with soilborne pathogens and augmented with earthworms (Lumbricus terrestris) could reduce disease of susceptible cultivars of asparagus (Asparagus officinalis), eggplant (Solanum melongena), and tomato (Solanum lycopersicum). Soils planted with asparagus were infested with Fusarium oxysporum f. sp. asparagi and F. proliferatum, eggplant with Verticillium dahliae, and tomato with F. oxysporum f. sp. lycopersici Race 1. In each host-disease system, earthworm activity was associated with an increase in plant growth and a decrease in disease. In general, plant weights were increased 60 to 80% and estimates of disease (area under the disease progress curve, percent vascular discoloration, and percent root lesions) were reduced 50 to 70% when soils were augmented with earthworms. Soil dilutions on selective media revealed that densities of fluorescent pseudomonads and filamentous actinomycetes were consistently higher for rhizosphere soils augmented with earthworms. In the studies with Verticillium wilt of eggplant, compared to the controls, the densities of total bacteria and Mn-transforming microbes were reduced in the presence of earthworms while population densities of bacilli and Trichoderma spp. were not affected. Disease suppression may have been mediated through microbiological activity. These studies suggest that strategies to increase earthworm densities in soil should suppress soilborne diseases.

Disease symptoms were observed in a commercial nursery in the midwest on Coreopsis verticillata 'Moonbeam' during the summer of 2006. Plants in a roughly circular area in one field showed foliar necrosis, stem basal cankers, root rot, and eventually plant death. Vascular discoloration was noted in stems of affected plants. Sporulation typical of Fusarium oxysporum was observed on the surface of cankers. Five isolates of F. oxysporum (KR1, KR2, KR4, MDU, and MDL) were taxonomically identified from monosporic cultures obtained from surface-disinfested stems and roots. All five isolates were vegetatively compatible with each other. Two methods of inoculation were used. Method one (conidial drench) involved pouring 100 ml of conidial suspension (10 6 conidia per ml) into 10-cm pots containing one healthy 2-month-old division of the same cultivar that was obtained from a different nursery. Method two (millet infestation) involved mixing autoclaved millet seed that had been colonized by each isolate into potting mix (2.5 g/L of mix) prior to transplanting. Four plants were tested per isolate per method and controls received distilled water or autoclaved millet. After 3 months, only two isolates (KR1 and KR2) inoculated by conidial drench caused root rot, whereas all isolates inoculated by millet infestation caused wilt, root rot, and vascular discoloration, and all inoculated plants died after 3.5 months Controls remained healthy. The fungus was recovered and was vegetatively compatible with the original F. oxysporum isolates. The tef-α gene from two F. oxysporum isolates was sequenced, submitted to the Blast ID search at Pennsylvania State University (1), and found to belong to the F. oxysporum species complex. Two isolates (KR1 and KR 2) have been deposited at the Fusarium Research Center at Pennsylvania State University under deposition numbers O-2437 and O-2438. Because of the popularity of this coreopsis cultivar, this disease has the potential to cause significant economic loss in nurseries and landscape businesses. The affected nursery, however, has taken all precautions to avoid disseminating the pathogen. Reference: (1) D. M. Geiser et al. Eur. J. Plant Pathol. 110:473, 2004.

Isolates of two biologically and phylogenetically distinct species, referred to as Fusarium solani f. sp. cucurbitae race 1 (Fsc-1 = Nectria haematococca mating population I [MPI]) and F. solani f. sp. cucurbitae race 2 (Fsc-2 = N. haematococca mating population V [MPV]), were suspected of causing an outbreak of Fusarium foot and fruit rot of pumpkin during 2001 to 2003 in Connecticut, New York, Ohio, and Missouri. Both species affect the fruit, but Fsc-1 also affects the crown and causes a stem rot. In this study, 156 isolates from affected plants and from soil under diseased fruit that tentatively were identified morphologically as members of the F. solani species complex were assayed for pathogenicity on pumpkin seedlings and mature fruit. Results of the pathogenicity assay indicated that 81 of the isolates were Fsc-1. The remaining 74 isolates were either nonpathogenic or only weakly pathogenic on the fruit. A subset of 53 test isolates from soil and plants, plus reference isolates of Fsc-1 and Fsc-2 and an isolate from wheat reported to cause a seedling rot on cucurbits, were characterized phylogenetically by sequencing a portion of the translation elongation factor 1-α gene. A BLAST query of the FUSARIUM-ID database at Pennsylvania State University indicated that 42 of the 53 test isolates were Fsc-1, whereas none were typed as Fsc-2. A polymerase chain reaction assay for mating-type (MAT) idiomorph revealed that all of the Fsc-1 isolates were MAT-1-2, suggesting that the pathogen may be strictly clonal in the affected fields. These findings provide convincing evidence that the Fusarium foot and fruit rot outbreaks were incited by Fsc-1.

Meloidogyne spartinae (Rau & Fassuliotis, 1965) was described from roots of smooth cordgrass (Spartina alterniflora Loisel) in Florida, Georgia, North and South Carolina, New Jersey, and New York (1,2). Affected plants were sampled in declining saltwater marshes at the Cape Cod National Seashore in Wellfleet, MA in May 2006 and Hammonassett State Park in Madison, CT in August 2006. Plants in adjacent, healthy stands were also sampled. Females, males, juveniles, and eggs of nematodes identified as M. spartinae were visible in roots stained with acid fuschin or were dissected from terminal galls at the root apex and from pockets in the root cortex where no galling was evident. The circular to ovoid terminal galls typically stopped root elongation. Morphological characteristics were used to identify this nematode as M. spartinae. Mature females in the root cortex were visible under a discolored lesion that appeared to result from a split in the cortex, probably from female expansion during development. Females were oval to lemon shaped with the neck protruding markedly to one side. Females also exhibited protruding perineal regions. In terminal galls, females were oriented toward the root tip; however, in the root cortex they were oriented either toward the root tip or toward the crown, with no obvious pattern. Egg masses were not observed and the eggs were deposited freely inside the gall or root cortex. Second-stage juveniles were long (730.3 μm, n = 60) with an elongate tail terminus. Males (2,203 μm, n = 40) were present in galls containing females. No morphological differences were observed between nematodes from the terminal galls or root cortex. M. spartinae was widespread in declining and adjacent healthy S. alterniflora. To our knowledge, this is the first report of M. spartinae from Connecticut and Massachusetts and the first report of M. spartinae development within root cortical tissues without gall formation. The role of this nematode in the sudden wetland dieback phenomenon (3) is being investigated. References: (1) J. D. Eisenback and H. Hirschmann. Nematology 3:303, 2001. (2) G. J. Rau and G. Fassuliotis. Proc. Helminthol. Soc. Wash. 32:159, 1965. (3) E. C. Webb and I. A Mendelssohn. Am. J. Bot. 83:1429, 1996.

During 2003, 10% of the Hiemalis begonias (Begonia × hiemalis Fotsch) developed wilt symptoms in a commercial greenhouse in Connecticut. Foliage turned a dull green, and stems developed a dark watersoaked discoloration near the soil line and had vascular discoloration. Stems, petioles, and leaves collapsed and became covered with sporodochia of a Fusarium spp. Single conidia were isolated from sporodochia and cultured on carnation leaf agar (CLA) and potato dextrose agar for 10 days. Isolates resembled Fusarium oxysporum, but the profuse sporulation with minimal aerial mycelium and the rare occurrence of polyphialides was consistent with the description of F. foetens (2). A comparison of a partial sequence of the 1-α elongation factor gene showed a 100% match with F. foetens. Inocula from five isolates were grown on CLA, washed from the plate, and adjusted to 10 6 conidia per ml. Suspension (50 μl) was injected into stems of healthy 6-week-old Hiemalis begonias cv. Barkos (one plant per isolate). Controls received distilled water. After 4 weeks, all inoculated plants turned dark and collapsed, and the same fungus was reisolated from these plants. Control stems remained healthy. An isolate (O-2348) has been deposited at the Fusarium Research Center at Pennsylvania State University, University Park. F. foetens has recently been described in association with a new disease of Hiemalis begonias in Europe (1). References: (1) R. Schrage, Phytomedizinischen Gesellschaft 33:68, 2003. (2) H.-J. Schroers et al. Mycologia 96:393, 2004.

Replanted asparagus fields commonly fail to produce a profitable stand due to alleopathic residues left behind from the previous asparagus crop, elevated densities of pathogenic Fusarium spp., and low densities of vesicular arbuscular mycorrhizae (VAM). Formononetin, a plant isoflavone that stimulates VAM spores to germinate, and sodium chloride (NaCl), a disease-suppressing amendment, were evaluated alone and in combination for their effect on reestablishing asparagus at two locations in abandoned asparagus fields. Greenhouse studies also were conducted with naturally and artificially infested soils. Formononetin was applied as a crown soak or soil drench, and NaCl was applied as a granular treatment. Feeder roots from soil cores sampled from field plots and from greenhouse transplants were assayed for colonization by VAM and for lesions caused by Fusarium oxysporum and F. proliferatum. Formononetin increased the number of VAM vesicles in roots from the field and greenhouse studies and reduced the percent root lesions caused by Fusarium spp. when compared with the nontreated controls. NaCl was more effective than formononetin in reducing the percentage of root lesions in both field and greenhouse experiment when compared with untreated plants but had no effect on VAM colonization. However, there was evidence that NaCl negated the effect of formononentin on VAM colonization. The NaCl treatment increased the May 2001 spear number by 15% and marketable spear weight by 23%. At one site, treatment with formononetin increased mean number of stalks per plant by 29% in 2000 and 14% in 2001. Both formononetin and NaCl improve growth and reduce disease of asparagus in replanted asparagus and may be useful in reestablishing asparagus in abandoned asparagus field.

The influence of soil densities of Fusarium oxysporum f. sp. cyclaminis on development of Fusarium wilt of cyclamen (Cyclamen persicum) was evaluated by adding increasing amounts of F. oxysporum f. sp. cyclaminis-colonized millet inoculum to potting mix planted to cyclamen. Additions of inoculum resulted in an increase in the CFU of F. oxysporum f. sp. cyclaminis per ml of potting mix and an increase in vascular discoloration of the corm of cyclamens after 10 weeks. A threshold of 5 × 10 4 CFU/ml of potting mix was needed to consistently cause vascular discoloration in the corms. Final fresh leaf weights declined to 30% of the leaf weights of the control when inoculum was added at 10 5 CFU/ml of potting mix. The effect of NaCl on Fusarium wilt was also examined, as anecdotal reports from cyclamen producers suggest that NaCl applications may improve plant growth. When NaCl was applied to potting mix at rates of 0.25 and 0.50 g/liter of potting mix, final fresh weights were greater and the area under the disease progress curve values were less than those of control plants. However, final disease severity was not affected. In the absence of the pathogen, leaf weights were greater when NaCl was added at 0.25 g/liter of potting mix. Disease development and the effectiveness of NaCl on disease were not affected by potting mix pH 5.1 to 7.2. Cyclamens grown in potting mix with a pH of 7.2 had chlorotic leaves, but with the addition of NaCl, the chlorosis was not observed. Leaf analyses showed that the addition of NaCl increased foliar levels of Na, Cl, and Mn, but decreased foliar levels of P, Ca, Mg, S, and B. Sodium chloride applied at 0.25 to 0.50 g/liter of potting mix had growth benefits, but disease suppression was marginal.

Twenty-six isolates of Colletotrichum gloeosporioides were isolated from diseased ornamental lupines (Lupinus spp. 'Russell Hybrids') in seven different nurseries in Connecticut from 1996 to 1998. Three isolates from New Hampshire, New York, and Utah were also included. All isolates identified were pathogenic on lupine and vegetatively compatible with each other. Representative isolates were compared to lupine isolates from Quebec, Canada and France (COL-1 group), and from Australia and France (COL-2 group). Both groups are responsible for causing anthracnose of ornamental and forage Lupinus spp. in these countries. The Connecticut isolates were vegetatively compatible with the isolates in the COL-2 group and had random amplified polymorphic DNA profiles consistent with isolates in the COL-2 group. Isolates in the COL-1 group were vegetatively compatible only with each other and had random amplified polymorphic DNA profiles that differed from the COL-2 group. Isolates in both COL-1 and COL-2 were sensitive to both benomyl and thiobendazole, but the COL-1 group could be distinguished as slightly more tolerant than the COL-2 group and the Connecticut isolates. These assays provided persuasive evidence that the isolates from Connecticut belong to COL-2 group. The introduction of this homogenous pathogen population in Connecticut is likely due to the importation of infested seeds.

Eggplants (cv. Midnite) were grown during 1996 to 1998 in soils naturally infested with Verti-cillium dahliae. Experimental plots were either mulched with black plastic or grown on bare ground and fertilized with either (NH 4 ) 2 SO 4 or Ca(NO 3 ) 2 at 224 kg of N per hectare each season. Compared to bare ground, mulch resulted in a 42 and 68% increase in 1996 and 1997, respectively. Compared to Ca(NO 3 ) 2 , (NH 4 ) 2 SO 4 fertilization increased yield by 22 and 18% in 1996 and 1997, respectively. In both years, there were no significant interactions between the mulch and fertilizer treatments on yield or on integrated estimates of the plant canopy growth curve or disease severity. However, the treatment effects were additive. When compared to bare ground, mulching increased the plant canopy 3 weeks after planting and reduced the percentage of symptomatic foliage 8 weeks after planting. Compared to Ca(NO 3 ) 2 , fertilization with (NH 4 ) 2 SO 4 increased the plant canopy after 6 weeks, but did not affect the percentage of symptomatic foliage. Mulching or (NH 4 ) 2 SO 4 fertilization increased the number of flowers compared to no mulching or Ca(NO 3 ) 2 fertilization, respectively. The rate of nitrogen fertilizer at planting or as a side-dress application did not affect growth or disease, but plants treated with (NH 4 ) 2 SO 4 were larger and had less symptoms than Ca(NO 3 ) 2 -treated plants. The use of black plastic mulch with (NH 4 ) 2 SO 4 fertilization complements one another and may reduce damage from Verticillium wilt on eggplant.

Sixty-seven samples of asymptomatic asparagus spears (avg. 26.5 spears per sample) were obtained during 1995 and 1996 from 22 retail markets in New Haven County, CT, from three commercial growers in Connecticut, and from experimental field plots in Connecticut and North Carolina. Surface-disinfested basal and apical segments were placed on media selective for Fusarium spp. Eight species of Fusarium were identified among 418 isolates from 1,776 spears. Of these, 30 and 62% were F. oxysporum and F. proliferatum, respectively. The incidence of Fusarium colonization was greater from the basal segments (15.5%) than from apical segments (8.1%). Spears shipped from Mexico, Peru, and North Carolina had higher incidence of colonization by F. proliferatum than spears shipped from California, Washington, or the northeastern United States. In both years, spears purchased during June had the highest incidence of F. proliferatum compared with other months. Since F. oxysporum and F. proliferatum are pathogens and infect asparagus crowns and roots, it is probable that infection originated in the field. The less frequent species were found slightly more often on apical segments than on basal segments.

Single potato plants (Solanum tuberosum) cv. Superior were grown in field microplots to evaluate the effects of spent mushroom compost or straw mulch on early dying of potato caused by Verticillium dahliae and/or Pratylenchus penetrans. Prior to planting, soil was fumigated, placed in field microplots, and then infested with pathogens. Area under the senescence progress curve (AUSPC) was greater for plots infested with V. dahliae and/or P. penetrans than for noninfested plots. Plants grown in soil infested with both pathogens developed symptoms earlier than plants grown in soil infested with a single pathogen. Both V. dahliae and P. penetrans reduced yields; the combination of pathogens reduced marketable tuber yields by 22 to 44% (A- and B-sized tubers). Although the total number of tubers of all sizes was not affected by cultural or pathogen treatments, the addition of compost increased marketable tuber weight and decreased AUSPC. Soil amendment with spent mushroom compost may be a means of reducing the effects of potato early dying and increasing tuber yield when one or both pathogens are present.

Single potato plants (Solanum tuberosum cv. Superior) were grown in microplots in soil that was fumigated and then infested with Verticillium dahliae, Pratylenchus penetrans, or both to evaluate the effects of these pathogens and of cultural treatments with spent mushroom compost or straw mulch on gas exchange of potato leaves. Photosynthesis and transpiration of terminal leaflets of a cohort of similar-aged leaves were measured once a week from the time of expansion until they senesced. Over all measurements, gas exchange per unit leaf area was less for plants in microplots infested with V. dahliae or P. penetrans than for those in uninfested plots. For leaves that expanded in early June, gas exchange was similar immediately after leaf expansion but declined more quickly when microplots were infested with one or both pathogens compared to no infestation. Overall, leaf gas exchange was increased by compost amendment but not affected by straw mulch. Compost amendment prevented some of the decline in gas exchange due to infestation by one or both pathogens. For leaves that expanded in July, compost increased the gas exchange immediately after expansion in both infested and non-infested plots.

The combined effects of rotation crops and nitrogen fertilizers were examined on the strawberry black root rot disease complex. In July 1995, microplots were filled with soil that had a history of strawberry black root rot and seeded with two types of oats (Avena strigosa 'Saia oats' or A. sativa 'Garry oats') or with sorgho-sudangrass (Sorghum bicolor × S. sudanense 'Triple S'). Microplots planted with 1-year-old 'Honeoye' strawberry crowns served as the controls. In May 1996, the crops were chopped and incorporated into the soil. The soil was re-planted with 1-year-old strawberry 'Honeoye' crowns and then fertilized with (NH 4 ) 2 SO 4 or Ca(NO 3 ) 2 at equivalent rates of N. Two months later, (NH 4 ) 2 SO 4 -treated plants had 36% more leaf area and 41% more runners than strawberries treated with Ca(NO 3 ) 2 Strawberries that had been pre- cropped with 'Saia' oats had 135% more runners and 38% more early fruit yield than strawberries grown in control microplots. Total fruit yield was not affected by the treatments. Compared to Ca(NO 3 ) 2 , the (NH 4 ) 2 SO 4 treatment reduced the percentage of blackened roots. The influence of the cover crops on growth and disease was stronger with (NH 4 ) 2 SO 4 fertilization than with Ca(NO 3 ) 2 fertilization. Combining 'Saia' oats or sorgho-sudangrass rotation with (NH 4 ) 2 SO 4 fertilization reduced lesion nematode (Pratylenchus penetrans) numbers in subsequent strawberry roots when compared to controls. Also, the combination of 'Saia' or 'Garry' oats as a pre-crop with applications of (NH 4 ) 2 SO 4 reduced black root rot severity when compared to controls. Only the 'Garry' oat rotation reduced strawberry root colonization by Rhizoctonia fragariae when compared to controls. Other effects were associated with using (NH 4 ) 2 SO 4 . The (NH 4 ) 2 SO 4 treatment lowered the rhizosphere soil pH by 0.2 units, reduced the numbers of fluorescent pseudomonads in the rhizosphere by 10- to 15-fold, and produced leaves that had more N, K, S, Mn, and Zn content than plants treated with Ca(NO 3 ) 2 . Rotation with 'Saia' oats combined with (NH 4 ) 2 SO 4 fertilization may suppress strawberry black root rot and increase yields through multiple effects on the host, pathogens, and associated microflora.

Growth chamber evaluation of several cultivars of basil and related herbs examined in the United States revealed that identical cultivars from different sources did not differ in their reactions to artificial inoculation with Fusarium oxysporum f. sp. basilicum. Cultivars differed in susceptibility to the pathogen: "Spicy globe" miniature was the most susceptible, and lemon basil (Ocimum basilicum var. citriodorum), Origanum majorana, and Thymus vulgaris were rated as not susceptible. Twenty isolates of F. oxysporum, originating from stems of diseased basil plants in Israel, were pathogenic on basil in growth chamber and greenhouse tests. Under artificial inoculation, 2 isolates of F. oxysporum f. sp. basilicum from stems were pathogenic to basil but not to 9 species representing Lamiaceae, Cucurbitaceae, Solanaceae, and Compositae indicating the specificity of the pathogen to basil. These isolates were used for additional resistance tests. Ocimum basilicum var. purpurascens (Exotic) and var. citriodorum were rated as not susceptible to the pathogen under artificial inoculation. Resistant germ plasm was identified in several basil plants of a local variety originally introduced from the United States and reselected at Newe Ya'ar. Seeds were planted in the greenhouse in naturally highly infested soil. Symptomless plants that survived in naturally infested soil were the source for F1 seeds of resistant germ plasm, which was confirmed by artificial inoculations with both isolates of the pathogen. Further selection tests to improve resistance were conducted up to the F4 generation in infested soil in the greenhouse. All individuals of the present genetic line remained symptomless, while all individual plants of the original susceptible cultivar defoliated 3 weeks after planting into infested soil, suggesting that the resistance may be a single, dominant gene. The causal organism was reisolated only from the susceptible plants and not from the symptomless resistant plants through all the experiments.

The effect of NaCl combined with Ca(NO 3 ) 2 or (NH 4 ) 2 SO 4 was examined on table beets (Beta vulgaris) in the presence and absence of Rhizoctonia solani (anastomosis group 2-2), the cause of Rhizoctonia root and crown rot. Transplants of cvs. Detroit Dark Red and Early Wonder grown in the greenhouse in infested soils and fertilized with Ca(NO 3 ) 2 (10 mmol of N) were 32% larger in dry weight than plants treated with (NH 4 ) 2 SO 4 (10 mmol of N). In noninfested soils, a 17% increase in dry weights was observed for plants treated with Ca(NO 3 ) 2 compared to plants that were fed (NH 4 ) 2 SO 4 . When NaCl (0.17 mmol) was applied, the mean dry weight sincreased 40% in noninfested soil and 12% in infested soil compared to plants that received no NaCl. No significant interaction occurred between N fertilizer and NaCl in greenhouse trials. However, in field soils infested with R. solani, NaCl (560 kg/ha) combined with (NH 4 ) 2 SO 4 (112kg of N per ha) produced 26 to 47% more root yield than when (NH 4 ) 2 SO 4 was used alone. Inthe absence of NaCl, Ca(NO 3 ) 2 suppressed disease more than (NH 4 ) 2 SO 4 , but adding NaCl to Ca(NO 3 ) 2 did not increase yield more than Ca(NO 3 ) 2 alone. The Cl salts KCl, CaCl 2 , and MgCl 2 did not significantly differ from NaCl in their ability to increase the dry weight of beets grownin infested soils. Leaf and root analyses revealed that (NH 4 ) 2 SO 4 applications increased N, P, S, and Mn in tissue more than Ca(NO 3 ) 2 applications. Applying NaCl increased tissue levels of Na, Cl, and Mn more than in plants that were not fed NaCl. All of the Cl salts had the effect of increasing concentrations of Cl and Mn in the plant. There was no evidence that the Na ion was disease suppressive. Chloride, however, may be of use in disease management of Rhizoctonia root and crown rot of table beets.