Case study – Using Actigard™ post-harvest for Psa control
Aidan Bourke grows about 25 hectares of kiwifruit in partnership with his parents in the Bay of Plenty in Wainui South, between Katikati and Tauranga. He does all his own spraying, which gives him the flexibility to apply products when needed throughout the season.
Both G3 and Hayward kiwifruit are grown on the property. Actigard is normally applied twice in the spring, and once in the autumn in combination with copper. Due to the high elevation of the orchard, picking is late. This means Aidan has time to apply only one Actigard spray post-harvest before leaf-fall.
Last year while applying Actigard post-harvest to a Hayward block, with just three rows to go, the spray tank emptied. Being an isolated orchard with no history of Psa, he thought it was unlikely to be a major issue, so he left the three rows untreated.
While mowing the orchard in the spring, he noticed Psa symptoms on almost all the male vines in the rows that had not been sprayed with Actigard the previous autumn. “There were secondary symptoms including curled leaves and exudate on the untreated male vines,” says Aidan.
“We did experience an extremely wet and cold winter last year. But the fact that those three rows did not receive the planned post-harvest application of Actigard appears to be the key factor in allowing Psa to infect those vines. We’ll make sure we get the post-harvest spray of Actigard on every block this season,” says Aidan.
An aggressive approach was taken in getting rid of the Psa infection, with a saw and rubbish bags. The males have now all bounced back, thanks to the comprehensive protection programme adopted on the orchard.
Actigard can be applied as a foliar spray up to four times per season in total (pre-flower and post-harvest). It’s best to apply the product as soon as possible after harvest, with the addition of copper to give fruit scars immediate protection until the Actigard kicks in (which can take up to 7 days). If canopy condition allows (i.e. leaves are still green), a follow up spray of Actigard should be considered 21 days later if infection risk remains high.
To avoid the risk of residues, extreme care must be taken to prevent Actigard drifting onto unharvested fruit. After applying Actigard, clean spray tanks, lines, and nozzles thoroughly before spraying vines yet to be harvested, and read the label completely before use.
Click here to download the Technote on Actigard for use post-harvest.