may-jun-2019

IN YOUR ORCHARD best results. A second spray, 10 to 14 days after the first, is becoming more common as growers and PCAs work to keep the orchard protected against increasing NOW pressure. As soon as all nuts from the first variety (usually Nonpareil) are split and ready for harvest, shake to get the nuts out of the trees. Nuts on the ground are very rarely targeted by NOW. Growers with isolated blocks and careful trapping programs can time their sprays to the NOW population activity (when egg-laying starts) instead of to nut vulnerability (hull split), if egg-laying is forecast to begin after hull split. Careful monitoring and the help of an experienced PCA are critical to making the best decision for spray timing to deliver the best possible crop quality. Slow (two miles per hour), careful spraying with high volumes of water (150 to 200 gallons per acre) are needed to deliver the best possible spray coverage and worm control in the tops of the large trees common in many almond orchards. These steps are more costly than spraying with faster speeds/lower volumes, but deliver the best NOW control possible. Finally, field check worm damage in the Nonpareil and consider a half spray to your pollinizers once the Nonpareils are picked up based on what you find. If the Nonpareil are clean, you may be able to get away without spraying the pollinizers. If you do decide to spray, be careful of the PHI. Harvest is tree shake timing when checking PHI, not nut pickup. Hull Rot This is a general term for hull infection by one or more pathogens beginning in early June with Monilinia hull rot and extending into hull split with Rhizopus or Aspergillus , both of which produce black spores between the hull and shell. Hull rot is difficult to control unless a grower goes all in and manages water using SDI and nitrogen (N) (summer leaf N levels not above at 2.5 to 2.6 percent), as well as carefully applies fungicides in early June (for Monilinia hull rot) or at the very beginning of hull split (2B stage of splitting, see photo) for Rhizopus or Aspergillus . Rhizopus and Aspergillus are wound pathogens, they can only enter a host through an existing opening. Hull split is that opening, allowing the pathogen a path to enter and infect the hull. Protecting the hull at the beginning of hull split reduces the chance that infection occurs. The spray timing critical to controlling Rhizopus (and perhaps Aspergillus ) hull rot is 2B (see photo in this article), the same timing for NOW control. Carefully selected, timed and applied fungicides are a key part of the best hull rot control possible (see efficacy of different fungicides in Time to Consider column in January/February issue or at www.ipm.ucanr.edu) . Spray Timing Hull split is a moving target and growers have a short window to get pesticides on the nuts to control NOW and hull rot. Proper timing of the early (2B, see photo) hull split spray for the best control possible is critical to the best control possible. Growers should be able to get across the orchard in no more than a week, and that probably means starting a little early and ending a little late in the beginning of hull split. If it takes more than a week to get across the orchards, focus your best timed sprays where the NOW and/or hull rot pressures are highest. Consider buying or borrowing another sprayer or using a helicopter (30 gallons per acre) to get your sprays on at the right timing. At early hull split, most of the splitting nuts are high in the canopy where helicopter spray coverage is best and ground spraying coverage can be poor. Ants When protein eating ants – pavement or fire ants – are present at harvest, significant crop loss can occur while the nuts are on the orchard floor. Studies have measured up to five percent damage when nuts are on the ground for 10 2B Hull Split. Can't be squeezed opened. 4 4 A L M O N D F A C T S