Succinate dehydrogenase inhibitor (SDHI) fungicides are currently represented in New Zealand by eight active ingredients bixafen boscalid carboxin fluaxapyroxad fluopyram isopyrazam penthiopyrad and sedaxane They are either currently registered or undergoing development in New Zealand for use against a range of ascomycete and basiodiomycete pathogens in crops including cereals ryegrass seed apples pears grapes stonefruit cucurbits and kiwifruit These fungicides are considered to have medium to high risk of resistance development and resistance management is recommended by the Fungicide Resistance Action Committee (FRAC) in Europe Guidelines are presented for use of SDHI fungicides in New Zealand to help avoid or delay the development of resistance in the fungal pathogens that they target

Seeds of Italian ryegrass perennial ryegrass wild oat winter wild oat phalaris and barnyard grass collected during the 2005/06 season were tested for dormancy and germination phenology between April and December 2006 In laboratory and outdoor environments dormancy was widespread in grass weed but not in ryegrass seeds The seeds of grass weeds had better germination in the outdoor environment than the laboratory In the outdoor environment only 15 of wild oat and winter wild oat 1963 of phalaris and 39 of barnyard grass seed germinated Protracted germination varied between species in two to seven flushes The earliest timing for effective postemergence grass control under the experimental conditions appeared to be about 6 weeks after sowing for wild oats and ryegrasses 12 weeks for phalaris and 14 weeks for barnyard grass The extended germination periods of phalaris and barnyard grass are a challenge to growers in designing a costeffective herbicide programme

No abstract

CAA fungicides are currently represented in New Zealand by the three active ingredients dimethomorph iprovalicarb and mandipropamid They are currently registered in New Zealand for use against oomycete fungi in grapes onions potatoes and lettuce These fungicides are considered to have low to medium risk of resistance development and resistance management is recommended by the Fungicide Resistance Action Committee (FRAC) in Europe Guidelines are presented for fungicide use that will avoid or delay the development of resistance to CAA fungicides

Anilopyrimidines have a site-specific mode of action and there is potential for resistance to develop in target plant pathogenic fungi. If resistance occurs, it is likely to arise through single-gene mutation. Resistance has not yet been recorded in New Zealand, but has been reported overseas in Botrytis cinerea, affecting grapes. Strategies developed under the auspices of the New Zealand Committee on Pesticide Resistance (NZCPR) to promote the use of anilopyrimidine compounds in a way which avoids or delays the development of resistance in pathogens of apple, grape and stonefruit crops in New Zealand are described.