Chitosan inhibited growth of Botrytis cinerea in liquid culture and suppressed grey mould on detached grapevine leaves and bunch rot in commercial winegrapes. Germination of B. cinerea was completely inhibited in malt extract broth containing chitosan at concentrations greater than 0AE125 g L )1. However, treated conidia were able to infect detached Chardonnay leaves and pathogenicity was not affected, even after incubation for 24 h in chitosan at 10 g L )1. When added after conidial germination, chitosan inhibited B. cinerea growth and induced morphological changes suggestive of possible curative activity. The effective concentration of chitosan that reduced mycelial growth by 50% (EC 50 ) was 0AE06 g L )1. As a foliar treatment, chitosan protected detached Chardonnay leaves against B. cinerea and reduced lesion diameter by up to 85% compared with untreated controls. Peroxidase and phenylalanine ammonia-lyase activities were also induced in treated leaves. In vineyard studies, Chardonnay winegrapes exhibited 7AE4% botrytis bunch rot severity at harvest in 2007 after treatment with an integrated programme that included chitosan sprays from bunch closure until 2 weeks preharvest, compared with 15AE5% in untreated controls and 5AE9% with fungicide treatment. In the following season, botrytis bunch rot severity was 44% in untreated Chardonnay at harvest and the integrated programme (21%) was less effective than fungicides (13AE8%). However, in Sauvignon blanc winegrapes, the integrated and the fungicide programme each reduced botrytis bunch rot severity to 4% and were significantly different from the untreated control (11AE5%). This study provides evidence that suppression of botrytis in winegrapes by chitosan involves direct and indirect modes of action.

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Botrytis cinerea is a fungus responsible for considerable damage to a wide range of crops worldwide including grapes Botrytis bunch rot caused by B cinerea is the major disease problem that must be managed by the New Zealand wine industry each season However the fungus is not easily managed as it can be both necrotrophic and saprophytic with a range of overwintering inoculum sources New Zealand grape growers have asked whether it is necessary to remove tendrils at the time of pruning in order to minimise botrytis bunch rot infection at harvest This review provides a summary of the information currently available on the importance of tendrils in the epidemiology of botrytis bunch rot under New Zealand conditions Gaps in knowledge and areas for further investigation are also identified

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Elsinoe leaf and fruit spot is a minor disease of apple and pear Very little is known of the biology and life cycle of the causal agent Elsinoe pyri The fungus was isolated from spots on apple fruit and grew very slowly on potato dextrose agar (PDA) The conditions needed for spore production were examined using different culturing media plating techniques and culture ages When small pieces of a 2 to 6weekold culture from PDA were subcultured onto corn meal agar for 2 days viable conidia were produced Conidial germination occurred between 10C and 26C with the highest germination percentage at 20C and 26C and greatest germination tube elongation at 20C At least 200 conidia per leaf were required to infect Royal Gala leaves Typical elsinoe spots were visible 6 weeks after inoculation Four months after inoculation conidia from the spots were reisolated onto PDA and grew into typical colonies of E pyri

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A survey of Integrated Fruit Production and organic apple orchards in Hawkes Bay in 201011 investigated sensitivity of Venturia inaequalis isolates to demethylation inhibitor (DMI) and dodine fungicides EC50 values from mycelial growth assays for two DMIs showed continued loss of sensitivity since the 1990s Sensitivity was lower in orchards where DMI usage exceeded resistance management guidelines The most DMIsensitive isolates were found in one organic orchard Plant inoculations showed that black spot control of myclobutanilresistant V inaequalis strains by one application of myclobutanil was only 55 compared with 99 for myclobutanilsensitive strains The study suggests that resistance to DMI fungicides has continued to develop that loss of black spot control could be expected in some orchards and that DMI resistance management guidelines need reviewing There was high sensitivity to dodine in all orchards (mean EC50 of 024 mg/litre) and no evidence of increased resistance since the 1990s

The effect of urea applied to apple leaves in autumn on production of ascospores of Venturia inaequalis (black spot) was quantified in four studies. Autumn urea at concentrations from 0-20% reduced ascospore production in spring in proportion to the log of the urea concentration. A single application of 5% urea sprayed onto fallen leaves gave an 88% decrease in ascospore production. Urea applied to apple trees before leaf fall significantly reduced black spot disease on leaves the following spring in cv. Fuji, but not in cv. Royal Gala. Ascospore production was reduced by the fungicide cupric hydroxide, but was not affected by a low concentration of fish fertilizer. Three methods of ascospore assessment were used to detect differences in ascospore production.