This paper reviews the subject of canopy management with an attempt to develop principles. These principles provide guidelines for canopy surface area amount; spacing between canopies; within canopy shade, especially for the fruiting/renewal zone; balance between fruit and shoot growth; and uniformity of location of fruit/renewal zones, shoot tips and cane bases. Field techniques of point quadrat analysis and canopy scoring are introduced as an aid to defining problem canopies. These techniques are cheap, quick and effective. A set of twenty-one numeric indices and descriptors to assess winegrape canopies is then presented as a winegrape canopy ideotype, which can be further used as management guidelines. Recent publications are reviewed from various aspects of canopy management. These include vigour control, shoot trimming, leaf removal in the fruit zone and training system responses. The paper concludes with presentation of the authors' unpublished data on the effects of canopy microclimate on yield and wine quality. The trial was conducted with the cultivar Cabernet franc on a deep, fertile soil in a cool, high rainfall region. Canopy division using the Ruakura Twin Two Tier doubled yield compared to dense, vertical shoot positioned canopies which are common in New Zealand. Shade caused reduction in all yield components, and also delayed fruit ripening and reduced wine quality. Similar results were obtained by comparing fruit production at different heights with the Te Kauwhata Three Tier trellis system, where lower tiers were shaded at the canopy exterior. The results confirm that grape yield and wine quaiity can be simultaneously increased by improved canopy management of shaded vineyards.
A series of experiments using potted plants in a glasshouse detached laterals in the laboratory and trees in the fi eld were undertaken to study wound size and number of Neonectria ditissima conidia required to produce European canker infections on freshlymade branch wounds in the apple cultivars Royal Gala and Scilate Th e wound types were needle and pin injuries rasp wounds and pruning cuts Spore concentrations from 102 to 106 conidia/ml and two inoculation methods (droplet and mist) were used Disease expression varied for the different assay types probably due to the conduciveness for infection of the diff erent incubation conditions Overall there was little eff ect on pathogen colonisation and lesion development based on injury type inoculation method or spore concentration >103 conidia/ml For freshlymade wounds such as pruning cuts or rasp wounds only three conidia were required for infection initiation in the glasshouse under highly conducive conditions 12 conidia in the laboratory on detached shoots and 10 to 30 conidia in the fi eld
The fungus Neonectria ditissima causes European canker of apple To determine the pathogenicity of different isolates conidial inoculum of each isolate needs to be prepared Freezing inoculum ensures that conidia do not germinate before inoculation and facilitates screening of large numbers of isolates In this study conidial suspensions of three different isolates and field conidia collected from apple cankers were used to inoculate dormant potted 1yearold Royal Gala trees in a glasshouse Each conidial suspension were removed and inoculated with four replicates of two shoots per treatment Significant differences in disease incidence and lesion size were observed between the different isolates at each assessment date 5 to 15 weeks after inoculation (P
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
In culture most isolates of Neonectria ditissima the causal organism of European canker do not produce conidia Those that do often produce singlecelled conidia rather than the typical multicelled conidia that are found in nature A series of experiments was conducted to determine the conditions needed for conidium production Four culture media (malt extract agar modified Matsushimas medium (MM) apple sap amended water agar (ASAWA) and water agar) five light regimes including darkness near ultra violet (NUV) light and white fluorescent light and three plate sealing patterns were tested Subculturing isolates producing large numbers of viable conidia of which 71 produced multicelled conidia Similarly under a white fluorescent light/darkness regime all isolates produced viable conidia on MM and ASAWA and 100 and 97 of the isolates produced multicelled conidia respectively
This study examined incubation period, lesion length and conidial release in Neonectria ditissima (European canker) in four New Zealand regions in relation to climatic factors. Incubation period was studied on potted ‘Royal Gala’ trees inoculated with N. ditissima. One week after inoculation, symptomless trees were dispatched to Waikato, Hawke’s Bay, Tasman, Otago and positive controls remained in a glasshouse. Conidial release was studied in trees with lesions that were dispatched to the same regions. Rain traps were placed under each lesion and conidia quantified after each rain event. Disease progress and conidial production were examined in relation to weather. Lesions developed significantly slower in Otago and faster in Waikato and the glasshouse, compared with Tasman and Hawke’s Bay. Symptom development accelerated with increasing daily hours of 11–16°C and humidity (74.6–87.2% RH). The highest conidium counts occurred in Waikato and the lowest in Otago, while conidial production started earlier in Tasman than elsewhere. Temperature is the main driver for symptom development during the incubation period and rainfall is not required. Rainfall frequency drives conidial production.
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