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Nectria haematococca Berk. & Broome causing stem girdling of three cultivars of greenhouse pepper, Capsicum annuum (cvs. Kelvin, Cubico, and Grizzly), was found for the first time in a single greenhouse in south Florida in March 1999. Approximately 10% of the plants were affected at first report increasing to over 40% within 3 months. Black lesions occurred at nodes where the plant was pruned or where fruit had been harvested. No mycelium or perithecia were noted in association with the lesions. All tissue above a lesion appeared normal until the lesion girdled the stem, causing the tissue above the lesion to wilt and die. The plant appeared unaffected below the lesion. The pathogen was isolated on half-strength Difco potato-dextrose agar (½ DPDA). Reddish perithecia developed readily in culture. Two single spore isolates of the pathogen obtained from two naturally infected plants (cultivar Kelvin) were used to satisfy Koch's postulates. Five plants of Kelvin were inoculated with each isolate by inserting a 4-mm agar block of the pathogen grown for 5 days on ½ DPDA into the stem. Five plants of the same cultivar were similarly treated with fungus-free ½ DPDA. Plants were grown under greenhouse conditions after inoculation. In four plants, black lesions similar to those seen in the commercial greenhouse developed within 1 week. In one plant, the portions of the plants above the point of inoculation wilted after 5 days. The upper parts of the plants appeared healthy until lesions girdled the stems. The plants treated with fungus-free agar remained healthy. The fungus was re-isolated from the margins of lesions on the inoculated plants. The pathogen has been reported to cause stem lesions and fruit rot of pepper in greenhouses in England (1) and Canada (2). Fruit symptoms were not observed in the Florida greenhouse. Stem symptoms were again reported from the same greenhouse in the following season. References: (1) J. T. Fletcher. Plant Pathol. 43:225–222, 1994. (2) W. R. Jarvis. Can. Plant Dis. Surv. 74:131–134, 1994.

Rio Grande Gummosis (RGG) is one of the most serious diseases of grapefruit in the Indian River region of Florida. Experiments were conducted to determine if a graft-transmissible agent was associated with this disease in commercial grapefruit, and if any such agent was present in scion sources used for grapefruit propagation. Indexing data from indicators revealed that 79% and 31% of the commercial grapefruit and scion trees, respectively, contained a psorosis-like agent (PLA). The PLA was present in both RGG-affected and symptomless trees. We conclude that Florida's grapefruit propagation sources are contaminated with a PLA that is now widespread in commercial plantings.

Powdery mildew was observed affecting mature, field-grown, fresh-market tomatoes in southeastern Florida (St. Lucie, Martin, Palm Beach, and Broward counties). Outbreaks were noted in May of 1996 and throughout the spring of 1997. Affected leaves were generally yellow and, in some cases, developed a purplish cast. Whitish areas of fungal growth were often seen in the middle of lesions, but were less prominent than that reported for powdery mildew of field tomato in Hungary (2). Microscopic examination revealed that conidia were produced in chains, contained no fibrosin bodies, and were not dimorphic. Conidial measurements were 33.2 × 15.6 μm, based on 21 samples of five conidia taken from five different fields. These measurements were similar to those for an Erysiphe sp. causing powdery mildew of greenhouse tomato in New York (1). Greenhouse-grown tomato plants, cv. Sunny, in the fourth-true-leaf stage were inoculated with conidia scraped from lesions gathered in commercial fields. A single-edged razor blade was used to transfer the fungus to the adaxial surface of the test plants. Powdery mildew symptoms were observed within 10 days of inoculation. Morphology and size of conidia taken from greenhouse plants were similar to those for original field samples. This is the first report of powdery mildew of field-grown tomato in Florida. References: (1) D. M. Karasevicz and T. A. Zitter. Plant Dis. 80:709, 1996. (2) L. Kiss. Plant Dis. 80:224, 1996.

SONODA, R. M., and J. B. BROLMANN. 1980. Differences in susceptibility of Stylosanthes hamata to Colletotrichum gloeosporioides. Plant Disease 64:553-554. Anthracnose incited by Colletotrichum gloeosporioides was more severe on accessions of Stylosanthes hamata indigenous to the southeast coast of Florida with 2N=40 chromosomes than on those with 2N=20 chromosomes. The 2N=40 S. hamata were found in four localized areas and the 2N=20 ecotypes were widely distributed along the southeast coast of Florida. The 2N=40 accessions had a smaller beak on their seedpods and grew more vigorously in forage evaluation tests. Further tests are needed to determine whether the two types are conspecific. Stylosanthes hamata L. is indigenous to the southeast coast of Florida and to various areas in the Caribbean, Central America, and South America (7). It is one of several Stylosanthes spp. being tested as a forage plant in south Florida (2). One of the limiting factors in the use of Stylosanthes spp. is susceptibility to anthracnose incited by Colletotrichum gloeosporioides (Penz.) Sacc. (5). The C. gloeosporioides attacking Stylosanthes spp. in commercial and experimental plantings in Florida was probably introduced on contaminated seed (4). The pathogen was not found in surveys of native stands of S. hamata (10) along the southeast coast of Florida. Most of the S. hamata accessions collected from southeast Florida in the summer of 1979 were highly tolerant to C. gloeosporioides when inoculated (10). Three accessions were moderately susceptible (10). The most susceptible line was similar in pod morphology, ie, short beak, to an accession collected in 1971 that had excellent agronomic characteristics (2) but whose forage yield was reduced by C. gloeosporioides (6). The accession collected in 1971 had 2N=40 chromosomes, whereas most S. hamata accessions have 2N=20 chromosomes (3). A study was conducted to determine if differences in susceptibility of S. hamata indigenous to southeast Florida coincided with differences in chromosome number and pod morphology. MATERIALS AND METHODS Descriptions of S. hamata collected from native stands of the species from Fort Pierce, FL, south to Key West during the past 10 yr (approximately 200 collection sites) were searched for Florida Agricultural Experiment Stations Journal