Sharp increase in Hayward leaf spot symptoms
17 November 2016
Growers have reported a sharp increase in the level of Psa leaf spotting in many Hayward orchards across the Bay of Plenty this week. High winds associated with rain are likely to have contributed to this, with spotting and flower bud infection more prevalent in wind-exposed blocks. For most areas, the Psa risk model shows weather-related risk events have occurred regularly over the past month, which has potentially led to a series of infection events. As temperatures rise, the timing between an infection event and visual symptoms shortens. It is likely that the apparent sudden explosion of symptoms we are now seeing is an accumulation of infections expressing at a similar time. Extended wet periods and poor ground conditions for spraying has also resulted in compromised spray cover on some sites. Hayward growers should consider timing of flowering when responding to these recent symptoms. A reminder that Keystrepto may not be applied within one week of flowering (male or female) and a JA is required. Keystrepto and copper can be tank-mixed. Actigard and copper applied together will provide both immediate protective cover and an elicited plant response to extend protection through flowering. Actigard may not be applied to flowers or fruit and care should be taken to avoid spray drift. For Gold growers, follow male pruning rounds with a protective copper cover. Do not apply sprays in poor drying conditions and if foliar applied “seaweed “ fertilisers are also being applied, maintain a 7-day interval between these and copper products. Skin sensitive periods for Gold3 occur around 21 days after fruit set and for Hayward, 14 days following fruit set.