jan-feb-2021

Every almond grower facing limited water availability should have copy of the 2015 publication Drought Management for California Almonds written by David Doll and Ken Shackel. If it has been a few years since this was done, check the distribution uniformity of your irrigation system this spring. Delayed Dormant Pest Management Orchard sanitation is the key winter insect pest management practice for most almond orchards in the state. This practice reduces NOW populations and the food and shelter for survivors. If you read this column before buds extend (before pink bud stage), there may still be some time to shake or poll mummies from the trees. The target mummy count going into bloom is 0.2 or two mummies per tree (averaged over 20 trees per acre). The lower target (0.2 mummies per tree) is recommended for high pressure sites, with the additional recommendation at these sites of less than an average of eight mummies on the ground under a tree. Mummies should be swept into windrows and shredded by March 1 using a flail mower at slow enough ground speed to ensure that all nuts are destroyed. Intact mummies after mowing can mean surviving NOW. When is the cut-off date for shaking or polling ? The UC IPM recommendation is to get the mummies out of the trees “before bud swell”. When buds begin to swell and gain weight there is more risk of removing buds (and possibly reducing yield) when shaking or polling to remove mummies. However, if low numbers of buds are removed, it may be possible to shake after bud swell. In recent research, late mummy shaking (after bud swell started but before open flowers) removed an estimated 1 7 to 25 percent of buds without reducing yield at harvest. The cut-off date for mummy removal in any year in any orchard is a grower decision requiring the balancing of potential income loss from worm damage at harvest with risk of yield loss from excess bud removal. Delayed dormant timing is an excellent opportunity for management practices for a number of almond pest including scale, peach twig borer (PTB) and bacterial spot where monitoring results or damage history show a need. Use dormant spur sample results to determine if scale treatment is needed. Consult with your Pest Control Advisor (PCA) regarding materials and rates for a delayed dormant spray for this damaging pest as well as PTB and bacterial spot if orchard history indicates a need. There are a couple of points to consider if planning a dormant/delayed dormant spray in this dry, possibly early bloom year. Label language limits use of certain fungicides to “before bud swell” so attention to labels and orchard conditions is especially important. Dry winters increase the risk of phytotoxicity from high rates (three to four gallons per acre) of horticultural oil, but that risk decreases, in my experience, once orchards bud swell (delayed dormancy) begins. IN YOUR ORCHARD 4 6 A L M O N D F A C T S