David Doll0 commentsMay 18, 2010Insects

Peach Twig Borer and May Spray Timing

Peach Twig Borer (Anarsia lineatella) (PTB) is a long time pest of almonds, being first reported in California in the 1880s. It was considered to be the worst pest of almonds until the arrival of the Navel Orange Worm in the 1940s. Today, it still remains an important pest because of its direct damage to the nuts, damage and feeding on green and new shoots – killing terminal growth, and the preference of PTB damaged nuts by navel orange worm. PTB can be found overwintering as a worm (larva) in a tiny cell (hibernaculum) within the crotches of one to three year old wood. They may also survive in pruning wounds and bark cracks. Larvae emerge around bloom and migrate up the twigs and branches where they tunnel inside the branch, killing the terminal shoot. This loss of terminal shoots and subsequent delay in growth can be very problematic for young orchards. Figure 1: Damage to terminal branches caused by Peach twig borer. PTB adults begin to emerge around late March/ early April. Adults are gray in color and are about a 1/4 to a 1/2 inch in length. The adults lay eggs on twigs during May and June which give rise to the second flight of moths in Late June/Early July. Second generation moths then repeat the cycle, causing damage and laying another generation of eggs. Figure 2: Peach twig borer larva causing damage inside an almond fruit/hull. Nuts become more susceptible to damage as they near harvest. Feeding on green nuts by PTB makes them more attractive to NOW. Branch damage, although problematic on young trees, is not considered an issue on mature trees. Cultivars differ in their susceptibility to nut damage, Merced and Thompson are the most susceptible, followed by Nonpareil, Fritz, Price, and Ne Plus Ultra.

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Franz Niederholzer1 CommentJanuary 18, 2010Insects

New pesticides are effective on Peach Twig borer in early sprays

Author: Franz Niederholzer, UC Farm Advisor Sutter-Yuba Counties Peach twig borers (PTB) are a key pest of almonds. Nuts damaged by PTB are preferred feeding sites of navel orangeworm (NOW). At a recent almond IPM meeting in the San Joaquin Valley, a leading independent PCA told the audience that a good NOW program included PTB control. Talk with your PCA and review reject sheets and moth traps to decide if PTB control is needed in your orchard. Dormant, delayed dormant, or bloom sprays (See this article about insecticides at bloom), with the proper pesticide, give effective PTB control when applied properly (every-row spraying and proper sprayer speed). Other effective timings include a spring or summer spray(s) timed using moth trapping data and degree days. Recently registered pesticides give excellent PTB control in research by Dr. Frank Zalom, UC Davis Entomology Department, in the Sutter/Yuba region (see table below). These materials are less toxic to operators and wild life, especially those that live in water. Consider these new materials as part of a PTB control program in your orchards. Organo-phosphate pesticides (Lorsban, diazinon, etc.) and pyrethroids (Asana, Warrior, Brigade, Baythroid, Mustang, etc.) are very effective on PTB, but can harm fish and other life in local streams if the pesticide moves to the water in drift or water runoff from rain or irrigation. Including a new pesticide in your PTB program in dormant to bloom also helps avoid pest resistance to organo-phosphates and/or pyrethroids.

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David Doll1 CommentJune 27, 2009Insects

Hull Split is Approaching…

Hull split is approaching the the central San Joaquin Valley. In Kern COunty, hullsplit of almonds has been observed on the edges of blocks and tops of the trees, and will progress rapidly from this point forward. Hullsplit is a traditional time of making an application of insecticide to reduce navel orange worm damage and late season mite pressures. Blanks, or unpollinated or aborted fruit, will split first before the rest of the crop. So, as a grower, what do we need to keep in mind during hull split? 1. Insect pest management, which includes Navel Orange Worm and Spider Mites. 2. Water Management to reduce the incidence of hull rot. We will cover point 1 today, and the disease hull rot later this week. 1. Insect Pest Management practices for Hull split. Spider Mites: A miticide will be necessary if a pyrethroid was used within the orchard. Pyrethroids target both spider mites and predator mite populations. Once the predator mites are reduced, the faster reproducing problematic spider mites can flare up, causing tree defoliation. It is essential to include a miticide tank mixed if spraying a pyrethroid. If not using a pyrethroid, scouting the trees can give you an idea if you need to include a miticide. Scouting for mites is simple, should be done in the morning when it is cool, and can give a good idea about the ratio of predator mites to spider mites in your orchard. Please refer to the University of California Integrated Pest Management page for information on how to scout for mites: UC IPM Scouting for Spider Mites. There are several miticides to choose from at hull split. The most commonly used include Acramite, Envidor, Fujimite, Kanemite, Oil, Omite and Zeal. Each of these products can be effective, depending upon populations of

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