Flower bud infection symptoms in high-risk Hayward orchards
Symptoms of female flower bud infection are being seen on some Hayward orchards which suffered bud-rot in previous years. Brown discolouration of sepals and fine droplets of moisture on the surface of the buds are likely indications of Psa-V presence. These symptoms may not necessarily have obvious leaf spot associated with them. Within the same blocks, presence of red exudate on terminal buds, collapsed shoots and infected buds on the ends of female canes are other signs of Psa-V.
Growers are recommended to preferentially remove infected buds in pre-flower thinning rounds, cut back infected canes, continue with a protective spray programme and consider a pre-flowering girdle to help with bud-rot control.
Recommended timing for a pre-flower girdling for bud-rot control is 16-30 days pre-flowering so growers should plan for this now.
All growers are urged to measure impacts of this treatment on their site. Leave some control vines amongst girdled areas or alternatively, girdle only a few vines within high-risk blocks and measure flower-to-fruit retention for treated and control vines. A methodology to assist growers has been developed by the Zespri OPC team.
Tool hygiene is essential when pruning and/or girdling within these blocks.