Jhalendra Rijal1 CommentMarch 22, 2017Insects

Seasonal Insect Pest Monitoring Updates in Almonds

This year has been a challenging year to conduct any winter cultural practices due to constant rainstorms and flood situations. By now, however, mummy nut removal from the trees and ground should have been completed. Orchard sanitation is a very effective cultural method to control navel orangeworm (NOW) in nut crops. Almond mummies not only harbor overwintering larvae (Fig. 1), but also serve as the resource for egg laying (Fig. 2) by NOW females in the spring, during which new nuts are not yet vulnerable to NOW infestation. For insect monitoring in almonds, we already passed the trap placement timing (February 15) for Oriental fruit moth (remember the biofix of OFM was February 16 last year). Put navel orangeworm egg traps out by March 15 (South San Joaquin Valley) or by April 1 (North San Joaquin and Sacramento Valleys). Use black egg traps filled with the almond meal + 10% crude almond oil. Hang the traps at head height on the north side of the Nonpareil tree, at least 5 trees in from the edge. Put one trap per 10 acres with at least 4 traps per orchard. Remember to change the bait frequently as wet and lumpy bait is not effective in attracting females for egg laying. The biofix of NOW egg laying was April 18 last year. Follow the link for the details. Pheromone traps and lures are available to monitor male NOW activity. Although the relationship between egg and pheromone traps has not been fully understood, pheromone trap capture data still helps in making NOW control decision. In the orchard with NOW mating disruption, use of the pheromone trap is strongly recommended to assess whether the mating disruption is working. Negligible to no moth capture is expected if the mating disruption is working properly. For San Jose scale,

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David Doll0 commentsMay 23, 2015Insects

Webspinning Spider Mite Management in Almonds

Written by David Doll (UCCE Merced) and David Haviland (UCCE Kern) As summer approaches almond growers need to be monitoring for webspinning spider mites.  The most common species during the summer are Pacific and twospotted spider mite, though on occasion strawberry spider mite can be found. As adults, all three mites look and behave similarly, even though control of Pacific spider mite is more difficult to control. Webspinning spider mites overwinter in the orchard under rough bark and ground litter. During the spring, usually in March and April, migration will occur from these places into the lower areas of the tree.  These early-season populations are typically small, do not reproduce quickly, and often become prey to early-season natural enemies.   However, as temperatures warm in late May through September, the populations increase rapidly, particularly if natural enemies are absent. In favorable conditions, a lifecycle can be completed in 7-10 days, with 8-10 generations a year. Spider mites damage leaves by sucking cell contents and damage initially appears as a light stippling. As populations increase, mites and their eggs become more visible, and eventually “webs” will appear around spurs and leaves. Leaves with high populations will fall from the tree, reducing carbohydrate production.  If leaf loss becomes severe there is a potential for crop loss the following year. Spider mites are most problematic in orchards that are dusty or where the trees are stressed.  Stressing factors can include insufficient irrigation, nutrient deficiencies, or excessive crop load. The most important factor in spider mite management is biological control.  When natural enemies are abundant, miticides are not needed.  When natural enemies are absent, control with even the best miticides can be short-lived.  The goal is to find a balance that relies primarily on natural enemies supplemented by miticides as needed. The most important predators

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David Doll1 CommentApril 12, 2013Insects

Managing Mites in Almonds with Abamectin

Written By David Haviland, Kern County UCCE Entomology Advisor For more than a decade abamectin has played a key role in mite management programs in California almonds.  When applied properly, early-season abamectin treatments typically provide good mite control through hull split, and in some cases throughout the season.  Unfortunately, recent reductions in the cost of abamectin have led to unnecessary use, and sometimes abuse, of abamectin-based products.  This has led to more and more cases of unsatisfactory mite control at a time when mite management has taken an elevated importance due to increased adoption of pyrethroids for control of navel orangeworm.  This article covers several considerations that should be made while using abamectin to insure that it works effectively and consistently. 

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David Doll2 CommentsSeptember 22, 2011Insects

Late Season Leaf Defoliation due to Web Spinning Spider Mites

A few farm visits and phone calls have been coming in over the concern of late season spider mites. In these orchards, mite populations have flared up, causing defoliation. These growers have been asking is they should spray for mite control. As always, the answer depends, but here are some thoughts to consider when making this decision: 1. Since harvest has been delayed, and many trees have experienced longer periods of water stress than normal. Tree stress attracts mites, which creates hot spots within weaker areas of the orchard. 2. Tree defoliation caused by mites rarely causes significant effects on next year’s crop. If defoliation occurs, some leafing out may be triggered by an irrigation. It is still advised to apply a post harvest irrigation even if the tree is defoliated. Damage is more significant on younger trees as loss of leaves in the fall reduces the amount of overwintering carbohydrates. 3. An application of a miticide should only be made in attempts to curb the population until cooler weather. In many cases it is not possible to control a flare up, but rather the application “buys time” until cooler temperatures/ less stressful conditions arrive. An application should be considered if the “hotspots” are starting to defoliate and the mites are moving outward into the orchard. 4. If mites are present, but very little defoliation is occurring, the best strategy is to “wait it out.” Some later season defoliation may occur, but the “damage done” would be minimal, thus not worth the time and expense of the spray. 5. Miticides to apply should target the adults stage. These include the products Acramite (bifenazate), Vendex (Fenbutatin-Oxide), and Desperado (Pyridaben/Sulfur). 6. It is very difficult to get effective coverage with a miticide spray due to the hydro-phobic nature of the webbing. Drive slow and use the proper rates

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