California Almonds – Warm, Dry Weather Prompts Pest Concerns Going Forward – AgFax

Almond trees blooming, petal drop. ©Sara Savary, AgFax Media

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  • Here is this week’s issue of AgFax Tree Crops.
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Owen Taylor, Editor
Jenny Holtermann, Contributing Editor

OVERVIEW

Varying amounts of rain are in the forecast through the weekend and at the beginning of next week. With wetter weather ahead, growers have been applying fungicides in parts of our coverage area.

Trees are mostly at petal fall, with some hardshell varieties still holding onto flowers. Leaves are sprouting now and the orchards are full of green.

Traps are being set for a range of pests, and that will continue throughout the month.

Dry and warm conditions so far this year continue to raise concerns about potential for heavier-than-usual pest pressure.

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CROP REPORTS

Nick Groenenberg, Independent PCA, Hanford

“Almond growers are busy applying bloom sprays. The second bloom application has been going out over the last few days in anticipation of wet weather in the forecast for the weekend and early next week. The first round of fungicides went out two weeks ago along with a ReTain application.

“Our area is well into petal fall across all varieties. Bees are still out in the field but will be leaving over the next two weeks. Some bee activity continues in later varieties.

“Bloom started early, then slowed down but then ended fast. Overall, bloom tended to drag out this year. Bloom is best described as ‘unpredictably normal’ this year. Weather was excellent in our area during bloom, which made for ideal pollination.

“With the lack of rainfall this season, growers are irrigating to keep up with tree growth. Growers are adding fertilizer now that the leaves are also out and the hair roots are starting to grow. The trees should be able to take up water and fertilizer now.

“Some growers are applying small amounts of water every week, while others are irrigating every other week. Growers know what works best for their system.

“We are monitoring for leaffooted bug and stink bugs and are also positioning puffers for navel orangeworm.

“Pistachio growers are currently into weed management. Transplant processing tomatoes are going in the ground. Egyptian alfalfa weevil sprays are underway to control leaf damage.”

 

Tony Touma, PCA, Bio Ag Consulting, Bakersfield

“Softshell varieties are towards the end of bloom and well into petal fall. Hardshell varieties are at 100% full bloom. Bloom started very slowly and then came on very fast. We had tremendous weather for bees to work, and our area had sunny days for a majority of bloom.

“Last year we had terrible weather during bloom, with very cold temperatures and minimal bee working hours – yet we actually produced one of the best almond yields in history. Time will tell what the 2020 bloom will produce.

“This year we are finding a lot of variation between blocks, depending on growers and yields from last year. Alternate bearing yield will be a factor in almonds this year. For growers who made 3,800 to 4,000 pounds an acre last year, it will be hard to bring in yet another bumper crop. We’ll have a better idea of crop size in a few weeks as nuts progress.

“Of our growers, 50% to 60% did not apply fungicide sprays this year. Rain is in the forecast for next week, and we will see how it progresses. Kern County doesn’t have a history of terrible disease problems because we tend to be drier.

“San Jose scale, peach twig borer and navel orangeworm traps are going into place, and that will continue over the next 7 to 10 days. Our goal is to have all the traps set by April 1 to begin regular monitoring. We already have found a few scale, although nothing to be concerned about yet. If scale is going to show up, it will be right now.

“We see spider mites in almost every location. Mites are coming out from the soil and moving up the tree. Last year we didn’t see any mites until June or July because of the rain. Nevertheless, they will not do any damage right now.

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“We are finding minimal stink bug in weeds throughout some orchards.

“With this dry winter, more irrigation is being applied now versus the past several years. Unseasonably more leaves are out this year, making fertilizer and irrigation more critical. Growers tend to be applying fertilizer through their drip systems, as well.

“Egyptian alfalfa weevil populations are evident and are being controlled through sprays. The weevils can eat leaves and chew the plant if uncontrollable. They come once a year and we treat them.”

 

Franz Niederholzer, UC Farm Advisor, Colusa, Sutter and Yuba Counties

“Our area had a change in weather since mid-week when we almost hit record temperatures, with highs in the low-80s in some areas of the Sacramento Valley. As of today (Friday, March 6), things are cooling, with a chance of rain this weekend.

“The predicted rainfall amounts depend on where you are in the Sacramento Valley, ranging from zero to a half-inch. The north and east side of the valley tend to get the most rain, around Chico and along the Highway 99 corridor north. Winds are coming out of the south right now (3/6), which is the wind that brings rain.

“Most growers sprayed a fungicide this week. We are generally past petal fall. Having a fungicide on at petal fall with a chance of rain in the forecast is a good idea. With the remaining flower tissue left on the buds of later varieties, as well as leaf development, the trees could be susceptible to a wide range of diseases. Anything from rust, scab, shot hole or even brown rot can occur as the bloom season tails off. It is a time where fungus and bacterial infections can happen, given the proper conditions.

“For a majority of growers, this was their first fungicide spray because it has been so dry. Some growers applied a full bloom spray with a FRAC 11 fungicide targeting plant-health benefits. Opinions this year have been mixed on the need for sprays.

“Irrigation is underway across the north state in both almonds and walnuts because we haven’t had measurable rain since the middle of January. Water on almonds has generally included nitrogen fertilizers.

“We began putting up pheromone traps for oriental fruit moth and obliquebanded leafroller last week. Navel orangeworm, peach twig borer and San Jose scale traps will go up next week at the Nickels Soil Lab. Traps have been going up early this year because it has been so warm. Heat unit accumulations since January 1 this year are similar to what we recorded in 2015, which was the earliest navel orangeworm biofix in many decades at the Nickels Soil Lab.

“If you are planning to use navel orangeworm mating disruption this year, it is better to get dispensers up early – before March 20 to ensure the pheromone is out in the orchard ahead of female emergence. Also, carefully mow any remaining sanitation windrows to ensure all mummies have been shattered.

“Prune bloom is well underway, about three weeks ahead of last year. We have completely different conditions this year versus 2019. Prune bloom started late in 2019, while this year it’s earlier than average.

“I’m hearing reports about early signs of walnut catkins emerging. That’s very unusual for this time of year.”

 

Aaron Beene, PCA, Simplot Grower Solutions, Merced

“We are gearing up to get wet this weekend. Rain is in the forecast for Saturday with a couple of tenths of an inch predicted. It’s supposed to clear up for a day or two after that, then more rain is expected on Monday night through Tuesday. The forecast calls for a quarter to a third of an inch.

“Full bloom in our area was two weeks ago. We are now at petal fall and leaf expansion. Any remaining petals will be gone by the first of the week after this storm.

“With the warm storms coming on, there are concerns of jacket rot, shot hole, the beginning of scab, and possible anthracnose. Sitting at two weeks post-petal-fall and with storms in the forecast, leaf diseases are a consideration. A significant amount of plant debris is in the trees now in the form of petal jackets, and that increases the probability of botrytis developing.

“About 75% of my growers completed their first spray at full bloom 2 to 3 weeks ago. Then, they were applying fungicide and plant activator enhancement products to increase nut retention. Now, they are coming back at petal fall and applying fungicides with nutrients for jacket rot. Only a few growers elected to hold off.

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“Growers are putting on ground fertilizers that are soil applied during irrigation. Next week, they will start heavily with nitrogen applications to keep up with the demand of a larger crop.

“Grower are anticipating higher yields this year. Averages were lower last year due to bacterial blast. This year we had perfect bloom weather, extended bee hours and ideal conditions. If there were ever conditions for a good crop, it would be this year.

“Insect monitoring will begin in a couple of weeks with our peach twig borer traps. We use peach twig borer products with fungicide in younger blocks and obliquebanded leafroller materials for hot spots.”

 

Jhalendra Rijal, Area IPM Advisor, Northern San Joaquin Valley

“The weather forecast is calling for a chance of rain today (3/7) in the Modesto area, with light, very brief showers.

“Almonds are at 55% jacket stage (3/6) for Nonpareil, based on one estimate. The other major varieties range from 40% to 65% jacket stage, according to that report.

“We set biofix for oriental fruit moth this year on February 25, and since then, 143-degree days have been accumulated (as of 3/7).

“The rest of our traps for peach twig borer and navel orangeworm went out the week of March 1. Be sure to finish grinding the mummy nuts with flail mowing by mid-March.

“In walnuts, codling moth traps will be going out soon. If codling moth pheromone for mating disruption is used in the orchard or if populations are influenced by a nearby orchard with a mating disruption program, regular pheromone lure rates (1x) do not work. PCAs need to use a lure that combines codling moth pheromone and a pear-ester (kairomone) lure called CMDA. This lure attracts both male and female in the orchards where a codling moth mating disruption program in place.”

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