No abstract

Products containing different gibberellic acids (GA) and GA inhibitors were applied to grapevines during the 2009/10 and 2010/11 growing seasons to evaluate possible effects on bunch architecture and subsequent botrytis bunch rot (BBR) severity In the 2010/11 season the timing formulation and dose responses of the GA inhibitors in association with a biological control agent were also evaluated for their effects on BBR In both seasons the effects on yield and fruit quality and quantity were also measured to determine whether the treatments might affect commercial production There were no significant differences in either BBR incidence or severity in either season between any treatments including the standard fungicide programme Bunch openness was significantly modified by treatments but with no consistent pattern

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

The recently developed herbicide saflufenacil was evaluated in six field trials between 2008 and 2011 for weed control in maize (Zea mays) crops Trial sites varied considerably in soil characteristics and weed spectrum No phytotoxicity or visual damage symptoms were observed in any of the six cultivars planted When used alone at 70 or 105 g ai/ha saflufenacil provided effective control of annual broadleaf weeds including atrazine and dicambaresistant fathen (Chenopodium album) but had little activity on grass weeds In combination with acetochlor both rates of saflufenacil provided good control of annual grass and broadleaf weeds in all but one trial In crops with a high weed pressure especially grass weeds a follow up postemergence herbicide would be required to maximise control Combinations of saflufenacil with up to 1200 g ai/ha of dimethenamidp were generally less effective than with acetochlor A strong negative relationship was evident between weed density and maize silage or grain yields

No abstract