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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Jhalendra Rijal0 commentsFebruary 15, 2016Insects

Monitoring and management of San Jose scale and other insect pests during the dormant season

This is the time of the year to assess the seasonal activities of certain insect pests in the orchard and make treatment decisions for the delayed-dormant spray. This evaluation provides guidance for planning in-season pest management activities. Insects that can be evaluated using dormant spur sampling includes tiny insects (Scales: San Jose scale, European fruit lecanium; non-webspinning mites: brown mites, European red mites), and overwintered worms (oblique-banded leafroller, oriental fruit moth, peach twig borer). Although dormant spur sampling does not cover navel orangeworm damage evaluation, it is critical to know how much percentage of the mummy nuts are infested with navel orangeworm larvae and follow the proper winter sanitation (see details here). Scale is a bit different in its lifecycle in comparison to other insects. It is a tiny insect that sucks the plant juices from the plant parts such as spurs, branches, fruits and foliage. SJS females are sac-like, legless insects that are covered by the protective shield, made up of waxy secretion. Since they don’t have legs to move, they are permanently attached to the host plant tissues and feed. Because of the protective cover, often, spray coverage is not sufficient to knock down the population especially in large and dense trees. SJS female and her offspring produce several thousands of progenies in one season. Feeding by a large number of scales can cause significant damage to fruit spurs and scaffolds, leading to reduced tree growth and productivity. In severe cases it can cause death of the new spurs and tree limbs in severe cases. So, knowing the density and/or activities of scales and the natural biocontrol activities on spurs is important for making a treatment decision. Spur sampling during the dormant season Use spur sampling (follow the UC IPM guidelines) Take 100 spurs randomly taken from 35-50 trees (inside/outside/high infestation area)

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Jhalendra Rijal0 commentsDecember 22, 2015Insects

Role of Winter Sanitation for Navel Orangeworm Management

Written by: Jhalendra Rijal, Area IPM Advisor, UC-Cooperative Extension (San Joaquin, Stanislaus, Merced) Navel Orangeworm (NOW) is a primary pest of almonds, pistachios, and walnuts, with other significant crops hosts such as fig, citrus, pomegranates. This pest was first introduced in southern California in 1942 potentially from Central and/or South America. Because of the wide host range, this pest was quickly spread to the entire Central Valley within 5-7 years of its first introduction, established and had become a major production threat in almond and other nut crop production. Adults are greyish-brown moths (about ½ inch long) with grey markings on wings. Eggs are laid in mummy nuts or in the nuts with initiation of hull-split. Tiny first instar larvae bore into the nutmeat and all stages of larva feed on nuts producing large amount of webbing and feces (i.e. frass). Larvae are white to pink with a reddish-brown head, and with a typical crescent-shaped markings on the second segment of the body just behind the head. The mature larvae (5th instar) can grow upto ¾ inch in size. Besides direct damage on nuts, NOW larval damage can lead to fungal infections, such as the mold that produces aflatoxin, known to cause carcinogenic and mutagenic effects on human. The larvae overwintered in mummy nuts that are in trees or on the ground. Among non-chemical ways of reducing NOW populations or damage include early harvest and winter mummy removal (i.e. sanitation).  Winter Sanitation of orchards during the winter is the most effective way to reduce the damage in upcoming season. Mummy nuts should be removed from the trees before bud swelling stage (late January/early Feb.) by shaking the trees or by hand polling. The nuts should then be destroyed on the orchard floor by discing or flail mowing by March 15. UC IPM

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