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In the spring of 1997, commercial plantings of daikon or Chinese radish (Raphanus sativus L. cv. longipinnatus) in the San Joaquin Valley, Fresno County, were damaged by a disease previously undocumented in California. Symptoms consisted of small (2 to 5 mm diameter), circular to oblong, brown to light tan leaf spots that contained concentric rings. Following rains in January, leaf spots proliferated, coalesced, and resulted in significant necrosis of foliage. An Alternaria species with conidia with prominent beaks and spores produced singly or in chains of two was consistently observed on and isolated from the host. Conidia from naturally infected daikon leaves had mean dimensions of 190.1 × 23.1 μm, with a mean beak length of 60.0 μm. The isolates were identified as Alternaria brassicae (2). Pathogenicity was confirmed by culturing six representative isolates on sterilized 20% V8 juice solution for 14 days under a 12 h light/12 h dark cycle, filtering the suspensions through cheesecloth, adjusting spore concentrations to 25,000 conidia per ml, and spraying suspensions onto 4-week-old seedlings of daikon cvs. April and Summer. Plants were incubated in a humid chamber for 48 h and then maintained in a greenhouse. After 5 days, leaf spots similar to the original symptoms developed on all inoculated plants. The pathogen was reisolated and identified as A. brassicae. Control plants sprayed with distilled water remained symptomless. The inoculation test was repeated and results were the same. With the method described above, daikon isolates were also inoculated onto the following A. brassicae hosts (1): radish (Raphanus sativus L. cv. EXCO 517), broccoli (Brassica oleracea L. subsp. botrytis cv. Greenbelt), Chinese cabbage (Brassica campestris L. subsp. pekinensis cv. Cha-Cha), and broccoli raab (Brassica rapa L. subsp. rapa cv. Spring Raab). After 5 (radish) to 12 (other hosts) days, similar leaf spots developed on all inoculated plants and A. brassicae was reisolated and identified. Control plants sprayed with distilled water remained symptomless. These inoculations were repeated and results were the same. For California, this is the first report of black spot caused by A. brassicae on commercially grown daikon. References: (1) S. T. Koike. Plant Dis. 81:552, 1997. (2) E. G. Simmons. Mycotaxon 55:55, 1995.

Over the past 5 years, commercial acreage of the leafy crucifer arugula (Eruca sativa) has increased greatly in the Salinas Valley (Monterey County), California, and the crop is an important component in packaged salad products. A foliar disease has affected this crop and at times reduced its quality to the extent that it could not be harvested. Symptoms consisted of small (1 to 4 mm in diameter), irregular, dark brown to black speckling on adaxial leaf surfaces. Speckling sometimes expanded into tan spots 3 to 8 mm in diameter. Corresponding abaxial surfaces usually supported white fungal growth typical of a downy mildew. Conidiophores had main trunks with dichotomous branches ending in slender curved tips. Conidia were ovoid in shape, measuring 22 to 25 μm long and 19 μm wide. The fungus was identified as Peronospora parasitica. Pathogenicity was established by gently pressing diseased leaves onto arugula test plants and incubating plants in a humidity chamber for 48 h. Downy mildew developed after 6 days and the same fungus was observed. Although this disease has occurred on this crop for several years, this is the first documentation of P. parasitica on arugula in California. A previously described foliar bacterial disease caused by Pseudomonas syringae (1) has similar symptoms, making field diagnoses difficult if fungal signs of the downy mildew are not present on the leaf. Reference: (1) S. T. Koike et al. Plant Dis. 80:464. 1996.

In 1997, commercially grown bell pepper in the Salinas Valley (Monterey County), California, developed a previously undescribed disease. Plant foliage became pale green and wilted. Crowns developed brown lesions that girdled the plants, resulting in plant death. White mycelia and small (2 to 3 mm), black, irregularly shaped sclerotia were observed on the outside of plant crowns and in the centers of stem cavities. Isolations consistently resulted in the recovery of Sclerotinia minor. Pathogenicity was tested by inoculating 2-month-old bell pepper plants (cv. California Wonder) with sclerotia from three pepper and three lettuce (Lactuca sativa) isolates of S. minor (seven plants per isolate). Six to 10 sclerotia were placed 1 cm below the soil line and adjacent to the plant crowns. After 8 days, plants inoculated with pepper and lettuce isolates developed symptoms similar to those found in commercial fields, and S. minor was recovered from all peppers. The uninoculated control plants developed no symptoms. This is the first report of bell pepper as a host of S. minor.

During the spring and fall of 1999, commercial plantings of the cut flower stock (Matthiola incana) in coastal regions of California developed a severe foliar disease. Abaxial leaf surfaces supported the extensive white fungal growth typical of a downy mildew. Adaxial surfaces of newly infected leaves did not show symptoms, but with time, leaves exhibited extensive, diffuse chlorotic areas and slight twisting. Infected plants were not acceptable for the cut flower market and, therefore, were not harvested. Sporangiophores had main trunks with dichotomous branches ending in slender curved tips that were 2.8 μm long. Sporangia were ovoid, measuring 22 to 25 μm long and 19 to 22 μm wide. The fungus was identified as Peronospora parasitica. Pathogenicity was established by gently pressing diseased leaves onto stock plants (cv. Avalanche), incubating plants in a humidity chamber (20 to 22°C, 100% relative humidity) for 48 h, and keeping plants in a greenhouse. Diffuse chlorotic leaf symptoms developed after 10 days, and the same fungus later developed on abaxial surfaces. Uninoculated plants did not develop downy mildew. Inoculations were conducted a second time, and the results were the same. This is the first documentation of P. parasitica on stock in California.

Chervil (Anthriscus cerefolium) is a culinary herb grown commercially in California. In 1999, chervil plantings in shade houses in coastal California exhibited symptoms of a previously undescribed disease. Tan to gray lesions, surrounded by pinkish tissue, developed on crowns and lower sections of stems. Affected stems wilted, and plants eventually collapsed and rotted. More than 50% of the plants in the early spring planting were diseased. White mycelium and large, irregular, black sclerotia (3 to 6 mm diameter) were observed on infected stems and crowns. Isolations from symptomatic stems, mycelium, and sclerotia produced colonies of Sclerotinia sclerotiorum. Following previously described methods (2), pathogenicity was confirmed by culturing isolates on potato dextrose agar and allowing the fungus to colonize sterilized toothpicks placed on the surface of the agar. The pointed toothpick tips were inserted ≈3 mm deep in stems of potted chervil. Sterile toothpicks were inserted in control chervil plants. All plants were incubated in a mist chamber for 48 h and then kept in a greenhouse. Two other hosts of S. sclerotiorum, cauliflower (Brassica oleracea var. botrytis cv. White Rock) and celery (Apium graveolens cv. Conquistador)were inoculated in the same way. After 7 to 10 days, symptoms and mycelium similar to those originally observed developed on inoculated chervil plants, and S. sclerotiorum was reisolated. Plants left for 14 or more days supported sclerotia. Chervil inoculated with sterile, uncolonized toothpicks did not develop symptoms. Results were similar for cauliflower and celery plants. Pathogenicity tests were repeated, and the results were similar. A separate set of chervil was inoculated by placing sclerotia at the base of plants; these plants also developed disease but at a much lower incidence ( References: (1) M. J. Hims. Plant Pathol. 28:197, 1979. (2) S. T. Koike. Plant Dis. 81:1334, 1997.

In 2003, a new disease was observed on commercial strawberries (Fragaria × ananassa Duch.) grown in multiple fields in Watsonville, CA. Initial symptoms consisted of brown lesions on the undersides of the sepals of strawberry flowers. The lesions coalesced and spread to upper sepal surfaces and anther bases. No leaf symptoms were observed. Fields affected with this disease appeared to have a greater number of deformed fruit, though incidence data were not collected. A gram-negative, blue-green fluorescent pseudomonad was isolated from lesions on King's medium B agar from both sepals and anthers from 23 of 24 samples from three different fields. All isolates were levan, oxidase, and arginine dihydrolase positive. The strains did rot potato slices but did not induce a hypersensitive reaction in tobacco (Nicotiana tabacum L. cv. Sansun), indicating that the bacteria belonged to Lelliot's LOPAT group IVa, P. marginalis (3). Isolates from strawberry were compared with pathotype strains of Pseudomonas marginalis pv. marginalis, P. marginalis pv. alfalfae, and P. marginalis pv. pastinaceae. The 16S rDNA sequence of type strain of P. marginalis (Z76663) was 97 to 99% similar to the four strawberry isolates sequenced (GQ845121). Identity was further supported by analysis of fatty acid methyl esters (MIS-TSBA version 4.10; MIDI, Inc., Newark, DE). Polymerase chain reaction using BOX-A1R primers (repetitive sequence-based (rep)-PCR [1]) resulted in DNA fragment banding patterns that were identical among strawberry isolates. These banding patterns were different from the three distinct patterns of the P. marginalis pathotypes. Pathogenicity on strawberry (cv. Albion) was confirmed in three experiments using four strawberry isolates originally isolated from plants from three different fields and the P. marginalis pathotype strains. Inoculum was produced by growing bacteria in nutrient broth shake cultures for 48 h (24°C) and washing and suspending the cultures in 0.01 M phosphate buffer (pH 7.0). Three to five attached strawberry flowers on separate plants were dipped in the bacterial suspensions (106 CFU/ml) or sterile buffer for 1 min. To maintain high humidity, flower buds were enclosed in plastic bags for 36 to 48 h and then incubated in the greenhouse (24 to 26°C). After 7 days, approximately half of the flowers inoculated with the strawberry isolates had symptoms on sepals that were identical to symptoms seen in the field. Additionally, reisolates obtained from the symptomatic, inoculated flowers were identical to those used to inoculate the plants as confirmed by LOPAT reactions and rep-PCR, thus completing Koch's postulates. Flowers dipped in phosphate buffer or the P. marginalis pathotype strains did not develop symptoms and no bacteria were reisolated. To our knowledge, this is the first report of blossom blight of strawberry caused by P. marginalis and the first report of P. marginalis on strawberry in California. P. marginalis causes leaf bud rot of strawberry in Japan (2). Further research is needed to determine if the strawberry isolates represent a new or previously described pathovar of P. marginalis. References: (1) N. A. Cintas et al. Plant Dis. 86:992, 2002. (2) T. Kijima et al. Bull. Tochigi. Agric. Exp. Stn. 36:59, 1989. (3) R. A. Lelliott. J. Appl. Bacteriol. 29:470, 1966.

Tomatillo is an important vegetable in Mexican cuisine. It is of Mesoamerica origin and now is grown widely in the Western Hemisphere. In 2011, 2% of commercially grown tomatillo plants in San Benito County, California exhibited severe stunting with foliage showing mosaic symptoms and leaf distortion. The fruits on infected plants were mottled and unmarketable. Flexuous filamentous-shaped virus particles of 800 to 850 nm long and 11 to 12 nm wide were observed from sap of the symptomatic plants with a transmission electron microscope. Sap from the diseased tomatillo plants reacted positively in an immunostrip assay for potyvirus (Agdia Inc., Elkhart, IN), indicating a potyvirus was associated with the disease. The causal agent was mechanically transmitted from the diseased field plants to six virus-free greenhouse tomatillo plants and all inoculated plants induced identical symptoms. The causal agent was also transmitted to Chenopodium quinoa and C. murale (chlorotic local lesions) and Nicotiana clevelandii, N. tabacum, and Physalis wrightii (systemic symptoms). The disease was also transmitted to tomatillo plants by the green peach aphid (Myzus persicae) in a nonpersistent manner (1-min acquisition access period and 1-min transmission access period with no latent period). To further identify the causal agent, total nucleic acids were extracted by a cetyltrimethylammoniumbromide (CTAB) method (2) and tested by reverse transcription-PCR using potyvirus degenerate primers CIFor and CIRev (1). An amplicon of approximately 700 bp from the diseased tomatillo was cloned and sequenced. Analysis of the 631-bp partial CI sequence (GenBank Accession No. JN601884) showed that the virus had 93.6% nucleotide identity and 100% amino acid identity with cognate regions of Turnip mosaic virus (TuMV) (GenBank Accession No. D10927). Our results indicated that the disease was caused by TuMV. To our knowledge, this is the first report of TuMV in tomatillo. Since TuMV has a wide host range and is readily transmitted by green peach aphids, TuMV could be a new threat to tomatillo production in California. References: (1) C. Ha et al. Arch. Virol. 153:25, 2008. (2) R. Li et al. J. Virol. Methods 154:48, 2008.

Mexican sunflower (Tithonia rotundifolia) is a plant in the Asteraceae that is grown commercially as a cutflower commodity and also as a beneficial insectary plant. In June 2012 in coastal California (Santa Cruz County), several fields of organic lettuce (Lactuca sativa) were interplanted with direct-seeded rows of Mexican sunflower (cv. Torch) in order to attract beneficial insects. When approximately 2 to 3 weeks from harvest, lettuce plants began to wilt and collapse. Lettuce crowns were decayed and covered with white mycelium and small (0.5 to 3 mm diameter), irregularly shaped, black sclerotia. These plants were confirmed to have lettuce drop disease caused by Sclerotinia minor (2). In addition, Mexican sunflower plants began to wilt and eventually died. Initial symptoms on crowns and bases of the main stems in contact with soil consisted of a light tan discoloration. These discolored areas turned darker brown, became necrotic, and later were covered with white mycelium and sclerotia that were identical to those found on lettuce. Symptomatic sunflower stems were surface disinfested and small pieces from the margins of necrotic areas were placed into petri plates containing acidified potato dextrose agar. Resulting fungal colonies were white, produced profuse numbers (approx. 39 sclerotia/cm2) of small black sclerotia, and were identified as S. minor. Six-week-old Mexican sunflower plants grown in a peat moss-based rooting medium in 5-cm square pots were used to test the pathogenicity of four isolates. Isolates were grown on cubed and autoclaved potato pieces and resulting sclerotia were recovered and dried (1). For each isolate, 12 plants for each of three cultivars (cvs. Fiesta del Sol, Torch, and Yellow Torch) were inoculated by placing 3 to 5 sclerotia 1 cm below the soil level and adjacent to the plant crowns/stem bases. Sterile sand was placed next to crowns of the control plants. Plants were maintained in a greenhouse at 22 to 24°C. Symptom development was rapid and after 6 to 7 days, inoculated Tithonia plants exhibited brown necrosis at inoculated areas. After 10 days, Tithonia crowns were decayed and plants wilted. S. minor was reisolated from selected necrotic crown and stem tissues. Diseased plants that were not used for reisolations later supported the growth of the characteristic white mycelium and black sclerotia. There were no significant differences between the Tithonia cultivars, and overall disease incidence ranged from 74 to 100%. Non-inoculated plants were asymptomatic. The experiment was repeated and results were similar. In addition, the sclerotia of the four Tithonia isolates were similarly inoculated onto sets of 12 romaine lettuce plants (cv. Green Towers). After 5 to 6 days, all plants developed lettuce drop disease and the pathogen was reisolated. To my knowledge, this is the first report of Mexican sunflower as a host of S. minor. These findings indicate that Mexican sunflower and lettuce are susceptible to the same lettuce drop pathogen, and that this beneficial insectary plant could increase soilborne inoculum of S. minor. Growers should therefore be aware of the host status of beneficial insectary and other plants interplanted with crops. References: (1) P. Chitrampalam et al. Phytopathology 101:358, 2011. (2) K. V. Subbarao. Plant Dis. 82:1068, 1998.

CAL-CORE is a network of researchers, farmers, extension professionals, industry and non-profit organizations dedicated to furthering research into organic strawberry and vegetable production in coastal California. Formed 9 years ago, we have worked on a variety of fertility, pest and disease management issues facing organic growers. Currently, our main effort centers on vegetable/strawberry rotations and different options for fertility and disease management. In a replicated field trial we compare treatments across a range of sustainability criteria: crop yield, nitrogen cycling and losses, greenhouse gas emissions, disease incidence, biocontrol of insect pests, soil carbon pools, and economics. Main treatments are 2 versus 4 year rotations with different crop combinations believed to be either suppressive of a major soil borne disease (Verticillium wilt), or more profitable but more conducive to disease. Superimposed on the rotations are fertility treatments (legume/cereal cover crop only, legume/cereal cover crop + compost + additional fertility amendments, cereal cover crop + mustard seed meal, or untreated control) and in the two legume/cereal cover cropped treatments anaerobic soil disinfestation (ASD, a promising option for controlling a range of soil borne diseases) is used for disease management prior to planting strawberries. Six network farmers also chose a sub-set of these treatments to test on their farms and compare to their own management practices. The study is in year 4 and all treatments at all locations are now planted to strawberries. Preliminary data show Verticillium wilt to be the major cause of yield loss in strawberry, and that ASD provided partial control, but mustard seed meal did not. Soil inorganic N pools are very dynamic with rapid release of nitrate from crop residues observed. Soil carbon is already declining in the bare fallow (no winter cover crop) treatment and in the 2 year rotation as compared to the 4 year rotation. This project will provide farmers with tools to improve their production systems, meet water quality regulations, and quantify climate-related impacts of these intensive organic systems.

Author(s): Turini, Thomas; Cahn, Michael; Cantwell, Marita; Jackson, Louise; Koike, Steve; Natwick, Eric; Smith, Richard; Subbarao, Krishna; Takele, Etaferahu | Abstract: Basic information for commercial iceberg lettuce producers, including information on crop climatic requirements, varieties, planting, fertilization, harvest, and marketing channels.

Author(s): Daugovish, Oleg; Cahn, Michael; Koike, Steve; Natwick, Eric; Cantwell, Marita; Takele, Etaferahu | Abstract: Basic information for commercial cabbage producers, including information on crop climatic requirements, varieties, planting, fertilization, harvest, and marketing channels.

Author(s): Daugovish, Oleg; Smith, Richard; Cahn, Michael; Koike, Steve; Smith, Hugh; Aguiar, José; Quiros, Carlos; Cantwell, Marita; Takele, Etaferahu | Abstract: Basic information for commercial celery producers, including information on crop climatic requirements, varieties, planting, fertilization, harvest, and marketing channels.

In June 2013, a commercial organic planting of Swiss chard (Beta vulgaris subsp. cicla) in Monterey County, CA, showed symptoms of a soilborne disease. Early symptoms consisted of delayed and stunted growth, with wilting of foliage during the warmer times of the day. Initially, a light brown discoloration developed on stems at the soil line. As disease progressed, a dark brown necrosis extended up the main stem and down along the upper portion of the taproot. In advanced cases, the plants collapsed and died. Extensive white cottony mycelium and numerous brown, spherical sclerotia, approximately 1 mm in diameter, developed externally on the lower stem, crown, and adhering adjacent soil. For this particular planting, approximately 10% of the 0.4 ha was lost. Sequentially planted sets of chard placed in other parts of the farm were unaffected. Isolations from necrotic plant tissues, sclerotia, and white mycelium all resulted in recovery of the same white fungus that in culture produced identical sclerotia but no other reproductive structures. Based on white mycelium, sclerotia morphology, and the presence of clamp connections at hyphal septa, the fungus was identified as Sclerotium rolfsii (1). Pathogenicity was tested by growing isolates on potato dextrose agar, drying the resulting sclerotia for 48 h, then burying 5 to 8 sclerotia adjacent to the crowns of healthy Swiss chard plants grown in pots. Three isolates were tested using 24 plants per isolate. Six control plants were inoculated with sterilized sand. All plants were incubated in a greenhouse at 22 to 25°C. After 8 days, inoculated plants began to wilt. By 14 days after inoculation, 100% of the inoculated plants showed symptoms identical to those observed in the field. One half of the plants were used for re-isolations, from which S. rolfsii was recovered from all necrotic crown and stem tissues. The other half of the plants were maintained in the greenhouse; these plants later supported the development of sclerotia. Sand-inoculated control plants did not develop any disease symptoms. The experiment was repeated and the results were the same. To our knowledge, this is the first report of southern blight of Swiss chard in California. Southern blight has not previously been found in this cooler, western part of the county adjacent to the Pacific Ocean; southern blight has been documented on other crops such as pepper, tomato, and chives (3) in the warmer eastern and southern parts of Monterey County. S. rolfsii has been reported on Swiss chard in Louisiana, South Carolina, and Cuba (2). References: (1) K. H. Domsch et al. Compendium of Soil Fungi, 2nd edition. IHW-Verlag, Eching, Germany, 2007. (2) D. F. Farr and A. Y. Rossman. Fungal Databases. Syst. Mycol. Microbiol. Lab. Online publication, ARS, USDA. Retrieved July 26, 2013. (3) S. T. Koike et al. Plant Dis. 78:208, 1994.

Radicchio (Cichorium intybus) is ranked 22 among crops in Monterey County, California, with a farm gate value of $19,531,000 (3). Beginning in 2002, a leaf spot disease of radicchio was observed in Monterey County. The disease began as small lesions and in some cases coalesced into larger, irregular spots. Lesions were maroon to dark brown; in some cases, the margins of brown lesions became dark maroon with aging. Each leaf spot was observable from both adaxial and abaxial leaf surfaces. Symptoms primarily occurred on the outer foliage of the heads, though on occasion the head cap leaf could develop lesions. Disease incidence in the first year resulted in up to 10% unharvested radicchio because of cap leaf infections or reduced head size if outer wrapper leaves were all removed; outbreaks in subsequent seasons were more limited. Bacteria forming yellow mucoid colonies were isolated from surface disinfested symptomatic tissue that was macerated and streaked onto sucrose peptone agar medium. Bacteria were gram negative, did not fluoresce on King's Medium B, and used esculin as a carbon source but used none of the other 48 carbon sources tested using the API 50 CH test strip. Nine isolates from symptomatic radicchio had the same DNA fragment banding pattern generated by repetitive extragenic palindromic sequence polymerase chain reactions (rep-PCR) using the BOXA1R primer. Amplicons of rpoD, dnaK, fyuA, and gyrB for multilocus sequence typing (MLST) were generated using a modification of the scheme developed by Young et al. (4) and sequenced by a commercial laboratory. Concatenated sequences of the four genes from the radicchio isolates were compared to the sequences available in the Plant Associated and Environmental Microbes Database (1). The genetic distance between the nine isolates from radicchio and pathotypes of Xanthomonas hortorum were 0.03 or less and MLST analysis indicated that radicchio isolates were members of the species X. hortorum (2). To complete Koch's postulates, freshly grown cultures were suspended in phosphate buffer and adjusted to approximately 5 × 108 CFU/ml. The inoculum was sprayed onto the undersides of leaves of 40-day-old radicchio plants (C. intybus cv. Leonardo). Plants were incubated at 100% humidity for 48 h and then moved to a greenhouse. Plants sprayed with buffer served as negative controls. For each of the two experiments conducted, there were three and six single-plant replicates per treatment. The buffer treated plants did not develop symptoms but the plants treated with isolates from radicchio developed leaf spots similar to those observed in the field with symptoms beginning to be visible after 5 days. The bacteria isolated from symptomatic tissue on inoculated plants were identical to the original strains when compared with rep-PCR, thus completing Koch's postulates. Results from the two experiments were similar. To our knowledge, this is the first report of X. hortorum causing a leaf spot disease on radicchio. The disease continues to occur sporadically on radicchio grown in coastal California. References: (1) Almeida et al. Phytopathology 100:208, 2010. (2) Bull et al. Phytopathology 101:847, 2011. (3) Lauritzen, Monterey County Crop Report, 2010; (4) Young et al. Syst. Appl. Microbiol. 31:366, 2008.

Growers in the Salinas Valley are not able to rotate away from lettuce to other crops such as broccoli, as often as would be desirable due to economic pressures such as high land rents and lower economic returns for rotational crops. This aggravates problems with key soilborne diseases such as Sclerotinia minor, Lettuce Drop. Mustard cover crops (Brassica juncea and Sinapis alba) are short-season alternative rotational crops that are being examined in the Salinas Valley for the potential that they have to reduce soilborne disease and weeds. Mustard cover crops have been have been shown to suppress various soilborne diseases and there are also indications that they can provide limited control of some weed species. However, no studies have shown the impact of mustard cover crops under field conditions on S. minor. In 2003 we conducted preliminary studies on the incidence of S. minor and weeds following mustard cover crops in comparison with a bare control or an area cover cropped to Merced Rye (Secale cereale). There was a slight, but significant reduction of S. minor infection in one of three trials following mustard cover crops. Mustard cover crops also reduced emergence of Shepherd's Purse (Capsella bursa-pastoris) and Common Purslane (Portulaca oleracea) these studies. Mustard cover crops have distinct nitrogen cycling characteristics. They were shown to reach a peak of release of nitrogen in 30 to 50 days following incorporation into the soil. The levels of nitrogen that are released by mustard cover crops were substantial and could be useful in nitrogen fertilizer programs for subsequent vegetable crops.

Vetches (Vicia spp.) are planted alone or in combination with other plants as cover crops in vegetable production areas of California. December 2001 through February 2003, purple (V. benghalensis) and lana woollypod (V. villosa subsp. varia) vetches in the Salinas Valley (Monterey County) developed a foliar disease. Symptoms were small (≤5 mm in diameter), circular to oblong, purple brown-to-red brown spots that were visible from the adaxial and abaxial leaf sides, and occurred lower in the plant canopy. White sporulation was visible in the spot centers. Stems were infected and had elongated, irregularly shaped, brown lesions that were 5 conidia per ml) onto direct-seeded, 8-week-old, potted purple and lana woollypod vetch (12 plants each). Plants were kept in a dew chamber for 48 h and maintained in a greenhouse (23 to 25°C). After 7 to 10 days, all plants developed the characteristic leaf spots and stem lesions, and R. sphaeroidea was reisolated from such symptoms. Plants treated with only water did not develop symptoms. However, because disease incidence on test plants was low, inoculum was also prepared in water amended with 1.0 ppm of Tween 20. Four pots each of purple and lana woollypod vetch were sprayed with amended or nonamended inocula, and plants were handled as described. After 10 days, plants inoculated with Tween 20 amended inoculum had significantly higher disease incidence and severity (purple = 83% of leaflets infected with a mean of 3.4 spots per leaflet; lana = 83% infected with a mean of 3.2 spots) than did plants inoculated with water-only conidial suspensions (purple = 27% and a mean of 0.4 spots; lana = 38% and a mean of 0.6 spots). Finally, two other vetches used in the Salinas Valley were inoculated with the two suspensions. After 2 weeks, common (V. sativa) and languedoc (V. sativa ‘Languedoc’) vetch showed no symptoms, and control plants of purple and lana vetch developed disease. All inoculation tests were repeated, and results were similar. To our knowledge, this is the first report of R. sphaeroidea as a pathogen of purple and lana woollypod vetches in California. Reference: (1) U. Braun. A Monograph of Cercosporella, Ramularia, and Allied Genera (Phytopathogenic Hyphomycetes) Vol. 2. IHW-Verlag, Eching, Germany, 1998.

In 1998, a new disease was detected on 3-week-old commercial broccolini (Brassica oleracea L. var. botrytis × B. alboglabra) transplants in a Salinas Valley, Monterey County, CA greenhouse. Initial symptoms were small (2 to 4 mm diameter) circular to angular, water-soaked spots. As the disease progressed, spots remained relatively small, but turned tan to brown. When diseased tissues were macerated and streaked on King's medium B, a blue-green fluorescent pseudomonad was consistently isolated. Strains were levan positive, oxidase negative, and arginine dihydrolase negative. Strains did not rot potato slices, but induced a hypersensitive reaction on tobacco (Nicotiana tabacum L. ‘Turk’). Fatty acid methyl ester analysis (MIS-TSBA, version 4.10, MIDI Inc., Newark, DE) indicated that strains had a high similarity index (0.82 or higher) to Pseudomonas syringae, and GN (version 3.50, Biolog, Inc., Hayward, CA) profiles also identified strains as P. syringae. The bacterium associated with the disease, therefore, was identified as P. syringae van Hall. Pathogenicity was demonstrated by growing inoculum in nutrient broth shake cultures for 48 h, misting the broth cultures (1×106 CFU/ml) onto broccolini (cv. Aspabrock), and subjecting the plants to 48 h of high humidity. Control plants were misted with sterile nutrient broth. After 4 to 5 days in a greenhouse, leaf spot symptoms developed on all inoculated broccolini plants, and reisolated strains were characterized and found to be P. syringae. Control plants remained symptomless. The results of two sets of pathogenicity tests were the same. Repetitive sequence-based polymerase chain reaction using the BOXA1R primer resulted in identical banding patterns for the broccolini pathogen and for known isolates of P. syringae pv. maculicola from crucifers. In host range testing, P. syringae pv. maculicolawas pathogenic to broccolini plants. The broccolini isolates and P. syringae pv. maculicola isolates had the same pathogenicity results when crucifers and tomatoes were tested as hosts; broccoli and cauliflower (B. oleracea var. botrytis) were infected, and tomato results were variable. These tests suggest that the broccolini pathogen is the bacterial leaf spot pathogen, Pseudomonas syringae pv. maculicola, that occurs on broccoli and cauliflower transplants (1). To our knowledge, this is the first report of this pathogen causing a disease on commercially grown broccolini. Reference: (1) S. T. Koike et al. Plant Dis. 82:727, 1998.

Myrtle (Myrtus communis) is a woody, evergreen plant used in California as a landscape shrub or potted plant. In 2000, a new root and crown disease was found in commercial nursery myrtle being grown as potted plants. Roots were necrotic and crown tissue was brown. Affected plants became gray-green in color, withered, and died. A Cylindrocladium sp. was consistently isolated from roots, crowns, and lower stems of symptomatic plants. Isolates were characterized by having penicillate conidiophores terminating in obpyriform to broadly ellipsoidal vesicles. Conidia were hyaline, 1-septate, straight with rounded ends, (50-) 53 to 56 (-58) × (3.5-) 4 to 6 μm, placing it in the Cylindrocladium candelabrum Viégas species complex. Single-conidial isolates (STE-U 4012 to 4018) produced perithecia with viable progeny of Calonectria pauciramosa C.L. Schoch & Crous when mated on carnation leaf agar with tester strains of Cylindrocladium pauciramosum C.L. Schoch & Crous (2). Matings with tester strains of all other species in this complex proved unsuccessful. Only one mating type of C. pauciramosum has thus far been found in the United States. Pathogenicity of representative isolates was confirmed by applying 5 ml of a conidial suspension (1.0 × 106 conidia/ml) to the crowns of potted, 5-month-old, rooted mytle cuttings that were subsequently maintained in a greenhouse (23 to 25°C). After 4 weeks, plant crowns and roots developed symptoms similar to those observed in the nursery, and plants later wilted and died. C. pauciramosum was re-isolated from all plants. Control plants, which were treated with water, did not develop any symptoms. The tests were repeated and the results were similar. This is the first report of C. pauciramosum as a pathogen of myrtle in California. The disease has been reported on myrtle in Europe (1). References: (1) G. Polizzi and P. W. Crous. Eur. J. Plant Pathol. 105:407, 1999. (2) C. L. Schoch et al. Mycologia 91:286, 1999.

Common groundsel (Senecio vulgaris, Asteraceae) is native to Europe and is now a common weed mainly in disturbed habitats of almost worldwide distribution. In November 2000, groundsel plants growing adjacent to lettuce fields in California's coastal Salinas Valley (Monterey County) showed symptoms of rust. In a 0.2-ha survey area, 75% of the plants were infected. Examination of weeds growing in four residential blocks also uncovered infected groundsel. Densely clustered, orange aecia were observed on leaves and stems. Stems were swollen where aecia had formed. Blossom and fruit formation was not notably reduced, although some involucral bracts were infected. Aeciospores measured 14 to 18 μm × 12.5 to 15 μm (fresh material). Telia were not found. The pathogen was identified as Puccinia lagenophorae Cooke, a rust fungus that is native to Australia and New Zealand and infects plants of the subfamily Asteroideae (family Asteraceae) (3). P. lagenophorae is an autoecious species forming only repeating aecia (stage I) and telia (stage III). There are six other rusts of Senecio that occur in the United States (1) that readily form aecia but not telia on Senecio spp. When only aecia are observed on Senecio, which is typical for P. lagenophorae (2), the following features can be used to differentiate it from these other species: no pycnia (stage 0) are formed; aecia are formed repeatedly; systemic growth that results in deformation of the host, including formation of galls with dense clusters of aecia on the stem; poorly developed aecial peridium; and aeciospores small, measuring 12.5 to 18.5 μm × 10.0 to 16.0 μm (4). In addition, P. lagenophorae forms aecia even at the end of the year in northern temperate zones, whereas heteroecious species form aecia only in spring and early summer (2). This is the first record of P. lagenophorae in North America. Specimens were deposited in the Arthur Herbarium, Purdue University. Outside its native habitat, this fungus has been found in Europe, Africa, the Middle East, and South America. There are about 60 known host species of P. lagenophorae (3) including ornamentals such as Bellis perennis, Calendula officinalis, and Senecio cruentus. The pathogen may have been introduced to North America via land from South America through Central America, or by the importation of ornamentals that were either infected with rust or infested with diseased groundsel. References: (1) D. F. Farr et al. 1989. Fungi on Plants and Plant Products in the United States. American Phytopathological Society, St. Paul, MN. (2) M. Scholler. Regensb. Myk. Schr. 6:1, 1996. (3) M. Scholler. J. Plant Dis. Prot. 105:239, 1998. (4) I. Wilson et al. Trans. Brit. Mycol. Soc. 48:501, 1965.

In January and February 1999, extensive dieback was observed on commercial basil (Ocimum basilicum) being grown in shadecloth greenhouses in coastal California's Salinas Valley. Symptoms were associated with stems that were high in the plant canopy and had cut ends resulting from multiple harvests of the foliage. Stems had brown discoloration extending from the cut ends toward the crown of the plant. Attached petioles and leaves turned brown and wilted. Profuse white mycelia were generally present externally on symptomatic stems, and occasionally large (>5 mm long) black sclerotia were found inside affected stems. In some shade houses approximately 20 to 25% of the plants were diseased. Isolations from mycelia, sclerotia, and symptomatic stems produced colonies of Sclerotinia sclerotiorum. Inocula for pathogenicity tests were produced by growing isolates on potato-dextrose agar, removing the resulting sclerotia, air drying them for 12 h, and placing them onto sterilized sand saturated with sterile distilled water. Sand cultures were incubated at 24 to 26°C in the light. After 4 to 6 weeks, apothecia containing asci with eight uniform ascospores developed from the sclerotia. Apothecial cultures were placed at the base of potted basil plants that had been trimmed to simulate harvest and placed in a humidity chamber. After 4 weeks, stem dieback was observed on test plants and S. sclerotiorum was recovered from symptomatic tissue. This pathogenicity test was repeated and the results were similar. Though this disease has occurred in the state prior to 1999, this is the first report of S. sclerotiorum on basil in California. This disease has been reported in North America from Canada and Louisiana (2,3). In contrast with reports from Europe (1), basal infections were not observed in the California greenhouses. References: (1) A. Garibaldi et al. Plant Dis. 81:124, 1997. (2) G. E. Holcomb and M. J. Reed. Plant Dis. 78:924, 1994. (3) T. C. Paulitz. Plant Dis. 81:229, 1997.

In the fall of 1996, commercial plantings of broccoli raab or rappini (Brassica rapa subsp. rapa) in the Salinas Valley, Monterey County, were damaged by a disease previously unreported in California. Symptoms consisted of small (7 to 8 mm in diameter), circular to oblong, brown to light tan leaf spots that contained characteristic concentric rings. An Alternaria sp. having conidia with prominent beaks and spores produced singly or in chains of two was consistently observed on and isolated from the host. Conidia from naturally infected broccoli raab measured 144.5 to 194.5 × 22.2 to 30.6 μm (beak length ranged from 33.3 to 75.0 μm). The isolates were identified as Alternaria brassicae (Berk.) Sacc. (2). Pathogenicity was confirmed by culturing five representative isolates on sterilized 20% V8 juice solution for 10 days under a 12-h light/12-h dark cycle, filtering the suspensions through cheesecloth, obtaining spore concentrations of 30,000 conidia per ml, and spraying suspensions onto 6-week-old seedlings of broccoli raab cv. Spring Raab. Plants were incubated in a humid chamber for 48 h and then maintained in a greenhouse. After 5 to 7 days, leaf spots similar to the original symptoms developed on all inoculated plants. The pathogen was reisolated and identified as A. brassicae. Control plants sprayed with distilled water remained symptomless. The inoculation test was repeated and results were the same. Because of the extensive plantings of cole crops in the Salinas Valley, isolates from broccoli raab were inoculated onto two sets each of broccoli (Brassica oleracea subsp. italica cv. Greenbelt), Chinese cabbage (Brassica campestris subsp. pekinensis cv. Cha-Cha), and Japanese mustard (Brassica campestris subsp. nipposinica cv. Mizuna), using the method described above. After 5 to 7 days, similar leaf spots developed on all inoculated plants and A. brassicae was reisolated and identified. Control plants sprayed with distilled water remained symptomless. This fungus does not appear to be a pathogen specific to particular cole crops in this area (1). For California, this is the first report of black spot caused by A. brassicae on commercially grown broccoli raab. References: (1) S. T. Koike. Plant Dis. 80:822, 1996. (2) E. G. Simmons. Mycotaxon 55:55, 1995.