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 Doll1 CommentJanuary 18, 2016Insects

Bloom Bt for Peach Twig Borer Control

Written by John Edstrom, UCCE Farm Advisor Colusa County, Emeritus Hopefully, the central valley will finally receive drought relief from recent El Niño driven storms. The resulting wet soil conditions, however, can prevent orchard access for many orchard operations including dormant sprays. Without dormant insecticide sprays, peach twig borer (PTB) populations can increase dramatically and threaten next years crop. Worm reject levels were troublesome and costly to many almond growers this past season and point to the need to control PTB. Besides kernel damage, twig borer feeding also kills young buds and shoot tips after bloom and deforms young tree scaffold limb development . Fortunately, growers have a very safe alternative to dormant sprays using Bacillus thuringiensis (or Bt) to control PTB during the bloom season without harmful side effects to applicators or the environment. Other insecticidal materials claim to be safe to bees but may negatively impact bee colony health. Bt has no adverse affects to any stage of honeybees or the health of the hive.  Bt is a natural bacterial based insecticide that is toxic only when ingested by lepidopteran larval stage pests and is completely safe to beneficial predators and parasitoids. Bt is exempt from pesticide use regulations and so is particularly useful near urban or environmentally sensitive areas. The bloom Bt control strategy has proven effective since its was developed in the 1990s during a time when regulations were restricting the use of the highly toxic organophosphate spray materials. Bt is a perfect fit for almond IPM programs. Its only down side is that multiple applications are needed for complete control. Fortunately, Bt products are inexpensive and can be tank mixed with fungicides applied for blossom and leaf diseases around bloom, so the total costs are comparable or less than standard insecticides. Generally, two sprays are

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David Doll0 commentsApril 6, 2015General

Mid-Spring Considerations/Update

The 2015 almond season is in full swing. Many orchards have went through their drop, fertilizer applications and irrigation have began, and pest management concerns are beginning to form. Below are some thoughts and considerations from recent field visits. 1. Crop development is ahead of schedule – by as much as a month. Kernel fill is beginning in many ‘Nonpareil’ orchards, meaning that ‘Butte’/’Padre’ orchards won’t be far behind. This timing is important as about 80% of the season’s nitrogen budget should be applied prior to kernel fill – which may occur as early as early May! Secondly, it indicates that at this point – “What you see is what you’ll maximally get” in regards to kernel size, and farming practices – more particularly irrigation practices – can only reduce crop size. 2. Peach Twig Borer’s (PTB) “May Spray” timing looks to be an April timing. In the Merced area, our traps picked up a biofix around March 15th, which means we will be approaching 300 DD in about 7-10 days. Keep in mind that the spring spray timing for PTB is 300-400 degree days after the biofix. It may also be possible for the May Spray to have some effect on NOW.  Frank Zalom (UC Davis Entomologist) has found through research trials that timing the spray to 100 DD post NOW biofix (egg traps) and around 400 DD post PTB biofix can provide good control of NOW and PTB at harvest. 3. Rain is predicted for Tuesday (the 7th). Hopefully some rain will fall in the valley to help with the multitude of water issues. This rain may also bring some potential for fungal disease – especially rust and scab. Consider an application if there has been a history of disease. This application can be made 1-2 days after the rain event and

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David Doll2 CommentsApril 17, 2014Horticulture

Pros and Cons of Earlier, Warmer Spring

A few discussions this week around an “earlier” than normal year for insects and nut development. We are somewhere around 10-12 weeks post bloom in the Northern San Joaquin Valley. Nut developing is progressing as expected. We have experienced higher than normal temperatures during stage one of growth which may lead to sizing issues – especially in later blooming varieties (i.e. ‘Fritz’) – similar to what we saw in 2013. Endosperm development should begin or has begun in most ‘Nonpareil’ and pollinator orchards. I suspect that kernel fill will be earlier, leading to an earlier ripening/hull-split/harvest timing.

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David Doll4 CommentsJanuary 17, 2013Insects

IGRs at Bloom: Bad Idea?

Recent IPM practices have advised the use of IGRs (*1) diflubenzuron (Dimilin) at bloom time to control PTB larvae. This timing has been shown to be highly effective. Work by several scientists, including researchers from USDA-Tuscon Haydeen Bee Research Lab, Ohio State University, Oregon State University, BASF, and UC Davis (*2), however, has suggested that this may not be the best timing for bee health. Below is a email sent by Dr. Mussen for distribution. It basically concludes that the bloom timing for IGRs may harm bees, and should be avoided if possible.  Delayed dormant and May spray applications of these products can and should be considered for PTB control. Email from Eric Mussen, UC Entomologist/Apiculturist:

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David Doll2 CommentsJuly 12, 2010Insects

2010 Hull Split time…

I feel that the majority of topics regarding hull split have been discussed in prior entries, so I thought I would briefly make a few points of considerations for 2010: 1). Navel Orange Worm (NOW)/ Peach Twig Borer (PTB): Both insects cause damage to almonds, often NOW damage hiding PTB damage. Both insects are susceptible to the same insecticides. The 2010 treatment window for the 2nd flight of PTB will be overlapping with hullsplit. This is good because we can make one spray for NOW and PTB. This is bad because in years were the 2nd PTB flight occurred during hullsplit, worm damage was higher.  If no PTB treatments have been made and no NOW/PTB treatments are scheduled, I would plan to make one within the coming week. Reduced risk products or pyrethroids will provide control for both worms. Related topics previously covered: Peach Twig Borer, Navel orange worm, and hull split insect management. 2). Apply pesticides slowly – do not exceed 2 MPH with spray rigs. 3). Hull rot: Hopefully nitrogen applications have ended. Plan to reduce water to 80% ET for the coming two weeks. By the last week of July, first week of august, resume full ET. This will help reduce hull rot. Please see the previous article on hull rot. 4). Mites: Haven’t been much of a problem this year, but keep in mind that the use of a pyrethroid at hullsplit will most likely cause a mite flare up by harvest. A miticide should also be applied at hullsplit if a pyrethroid is used. There are a few products available that can knock down high populations of spider mites should a flair up occur. It is critical that these products are applied before webbing appears. 5). Harvest: Hullsplit appears to be a week later this year, suggesting that harvest will be

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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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