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The second and third generations of Lobesia botrana can cause both yield losses and spreading of grape bunch rots. The aim of this study was to know to what degree these generations of L. botrana influence the rots at harvest time. The study was carried out in two grape-growing areas of northeastern Italy where the moth completes two and three generations per year, respectively. In the context of 12 insecticide trials, samplings were conducted in different plots to estimate the number of larval nests of the second and third generations and that of rotten berries at harvest time. The data sets (number of larval nests and rotten berries) from the different trials were submitted to regression analyses. Gray mold was the most important grape rot. The second generation, in the area where L. botrana has only two generations per year, and the third generation, in the area where the moth completes three generations per year, can favor gray mold on and around berries bored by larvae. In contrast, groups of rotten berries non-contiguous to larval nests did not appear to be influenced by moth activity. In the area where the moth completes three generations per year the larval nests of the second generation did not show a significant influence on bunch rots at harvest time. [ABSTRACT FROM AUTHOR]

From 2004 to 2006, 213 isolates of Botrytis cinerea never exposed to Q center inhibitors (QIs) were collected to determine the baseline sensitivity to azoxystrobin. In the absence of salicylhydroxamic acid (SHAM), the mean EC values were 10.49 ± 13.12 and 0.36 ± 0.48 mg l for inhibiting mycelial growth and conidium germination, respectively. In the presence of SHAM, the mean EC values were 2.24 ± 1.29 and 0.22 ± 0.11 mg l. In 2010, five azoxystrobin-resistant isolates were detected with the resistance frequency of 2.25% in greenhouse tomatoes after 4 years of continuous exposure. These resistant isolates showed cross-resistance to other QIs but not to boscalid. In addition, these resistant isolates had comparable growth, sporulation and pathogenicity ability as sensitive isolates and maintained resistance in plants and the presence of SHAM. The G143A point mutation predicted to cause a change from glycine to alanine at codon 143 of cyt b gene was found in all resistant isolates. [ABSTRACT FROM AUTHOR]

A collection of Trichoderma isolates, with different biocontrol capabilities, were identified by molecular methods. Arbitrarily-primed PCR (ap-PCR) using repeat motif primers was performed on DNA from a Trichoderma spp. collection of 76 isolates, and representative isolates were further characterized into three main clades by internal transcribed spacer (ITS) sequence analysis. Consequently, a reliable phylogenetic tree was constructed containing isolates belonging to the T. harzianum clade (comprising T. aureoviride, T. inhamatum, and T. virens), the T. longibrachiatum and T. saturnisporum cluster, and that including the species T. asperellum, T. atroviride, T. koningii and T. viride. [ABSTRACT FROM AUTHOR]

Chitosan-copper complex compared with chitosan alone enhanced suppression of Botrytis cinerea rot development on four-true-leaf cucumber seedlings in controlled growth chambers. This paper constitutes the first report of such enhancement. The optimal concentrations for the most effective suppression of Botrytis development were 0.2 g l −1 chitosan and 1.6 mmole copper. After 12 days’ incubation, marked and significantly better disease suppression was obtained with chitosan-copper complex (75% suppression) than with chitosan alone. The chitosan-copper complex could be a very promising decay control agent for use in both conventional and organic agriculture. [ABSTRACT FROM AUTHOR]

Leaf populations of Trichoderma were studied on tomato, pepper and geranium plants incubated under various conditions. Treatments involved high (>90%) or lower (75-85%) relative humidity (r.h.), temperatures of 15±3°C or 25±3°C, and soil fertilization with formulations of 2,2,5%, 3,3,8% or 5,3,8% NPK. The size of populations on leaves treated with the fungus Trichoderma harzianum differed according to plant species, leaf age, length of incubation, atmospheric conditions, and plant nutrition. T. harzianum populations were promoted in many cases by high r.h. and by 3,3,8% NPK. Interactions of introduced populations of Botrytis cinerea with populations of T. harzianum on tomato leaves under combinations of the above conditions showed that the population of B. cinerea was ca tenfold lower in the presence of T. harzianum than in the absence of this fungus. [ABSTRACT FROM AUTHOR]

Small spots are a newly-defined manifestation of Botrytis cinerea infection on phylloclades of ruscus. The dark, water-soaked spots encircled by a faint halo, which are found on young phylloclades, become brown lesions later but do not grow in size. Control of all symptoms caused by B. cinerea on ruscus ( Ruscus hypoglossum L.), i.e., phylloclade rot or restricted lesions, upper branch rot, and stem canker, was achieved by sprays of fenetrazole (alone), diethofencarb + carbendazim, vinclozolin (alone) or alternately by sprays of diethofencarb + carbendazim, polyoxin B, and polyoxin D. Delay of disease development was achieved by copper sulfate pentahydrate and by the spray adjuvant Nufilm at a high rate of application. Mixing vinclozolin with copper, fenetrazole, TMTD or Nufilm did not control disease better than vinclozolin or fenetrazole alone. Postharvest control of gray mold (up to 72% reduction) in mature branches stored at 18°C was achieved by some of the above mentioned fungicides and by dichloftuanid, tebuconazole (alone or mixed together), iprodione, polyoxin AL, and vinclozolin + TMTD. Measures designed to improve field control of Botrytis epidemics in ruscus are discussed. [ABSTRACT FROM AUTHOR]

Difluoromethylornithine (DFMO) - an inhibitor of polyamine biosynthesis, and the polyamine spermidine (Spd) reduced gray mold of tomato, pepper, eggplant, bean and Senecio sp. leaves, and of rose petals by 37-88% when applied at 0.1-1.0 mM each. Higher doses did not result in better control. The disease was also reduced significantly on tomato fruits by 1.0 inM DFMO and by 0.1-1.0 mM Spd, and on cucumber fruits by 0.1-1.0 mM of both compounds, but not on grape berries. The combination of 0.2 mM DFMO with 1.0 mM Spd controlled gray mold of Senecio sp. and tomato leaves additively better than either treatment alone, whereas this effect was not observed in leaves of lettuce and pepper. Ethylene production was reduced significantly by Spd applied to leaves of tomato and pepper, but not by DFMO. Linear growth and germination of the fungus were affected by lower concentrations of DFMO (ED50 0.12-0.97 and 1.4, respectively) as compared with Spd. Spermidine and DFMO controlled white mold (Sclerotinia sclerotiorum) as effectively as did the fungicide benomyl. [ABSTRACT FROM AUTHOR]

Microclimatic variables were monitored in cucumber crops grown in polyethylene-covered, unheated greenhouses in Israel during the winter of 1987/88. The winter was characterized by a relatively large number of rainy days. The relative humidity (RH) in the greenhouses was high (>97%) during most of the day, resulting in long periods of dew persistence. Dew point temperature and duration of dew deposition were calculated for the plant canopy. Disease incidence was monitored in 2-m-high plants, both on senescing female flowers ('fruits') and on stems. Multiple linear correlations were calculated for gray mold incidence and duration of air temperature and RH at specific ranges, and of leaf wetness (LW). Disease was characterized by two stages, according to the rate of its development and the microclimatic conditions influencing it. In the first phase of the epidemic a high correlation was found between infected fruits and air temperature in the range of 11-25°C, and RH in the range of 97-100% or LW. In the second phase, disease incidence was better correlated with air temperature in the range of 11-16°C and RH above 85% (R = 0.681); there was no correlation between disease and LW at this stage. Development of stem infections was correlated with air temperature in the range of 11-16°C during the first phase of the epidemic. By contrast, the second phase was characterized by a close correlation between stem infections and RH in the range of 80-100% but also with air temperature in the range of 11-16°C, or with air temperature in the range of 11-25°C and RH 80-100%, and LW. [ABSTRACT FROM AUTHOR]

Survival- of Botrytis cinerea was monitored during two summer seasons. Mycelium and conidia were found dead on the surface of plant debris within 2 months of incubation, whereas a high level of viability was detected in thallus of the pathogen which was 1-2 mm inside the dry host tissue. Of the 148 samples of infected senescing cucumber female fruits, 8% survived seven warm months; half of these isolates of B. cinerea were resistant to dicarboximides (5 (µ/ml iprodione). Of the stems of cucumber infected with B. cinerea in winter, 18% yielded the pathogen at the beginning of the following winter; 15% of the surviving isolates were resistant to dicarboximides. Cucumber seedlings artificially infected by B. cinerea did not yield the pathogen longer than 9 weeks after establishment of infection, even when incubated in the shade. Plant debris with symptoms of gray mold were kept in the shade during the summer; at the beginning of winter it was possible to establish infection of B. cinerea from the dry debris. [ABSTRACT FROM AUTHOR]

Leaves of Pelargonium domesticum and Ruscus hypoglossum infected by Botrytis cinerea Pers., produced 12 and 1.5 nl ethylene/h/g, respectively, 34 days after inoculation; wounded or healthy leaves and phyloclades of them produced much lower amounts. When the fungus was grown on dead leaves it produced negligible amounts of the gas even when supplemented with methionine. Exogenous ethylene enhanced gray mold development in both hosts. Silver thiosulfate, aminooxyacetic acid (AOA) and aminoethoxyvinylglycine significantly inhibited disease development in pelargonium, and the latter two compounds inhibited ethylene production. AOA inhibited disease development and ethylene production in cut rose flowers; calcium ions inhibited disease development whereas the chelator EGTA [ethylene glycol bis-(β-aminoethyl ether)N,N,N′,N′-tetraacetic acid] enhanced it. Disease suppression by an excess of Ca was correlated with repression of ethylene production by the flowers, whereas deficiency in Ca increased disease severity. [ABSTRACT FROM AUTHOR]

Failures to control gray mold with vinclozolin and iprodione in cucumber greenhouses in Israel, during the winter and spring of 1981, were attributed to the development of resistance to dicarboximide fungicides in populations of Botrytis cinerea Pers. In seven out of eight greenhouses where resistance had been found in 1981, most or all of the B. cinerea population was resistant also in January 1982. This demonstrates the capability of resistant strains to survive during the warm and dry Mediterranean summer, and to provide competitive inoculum for crop infection in the subsequent winter. [ABSTRACT FROM AUTHOR]