Time to Monitor What's Bugging Almonds

As we say good-bye to March and another rain-starved month featuring above average temperatures, almond growers are telling us that something has been bugging them lately.

Leaffooted plant bug.

Leaffooted plant bugs are becoming troublesome and could cause nuts to fall off the trees in the coming month or the kernels to shrivel by harvest time, says field scout Jenna Horine.

 

Lately, Jenna has been fielding calls from farmers detailing the pest problem, especially in orchards on the warmer west side, where the crop tends to develop faster. The pests are looking for food and emerging locations such as neighboring fence lines, riparian areas and fields that have been fallow for years.

Here's an egg mass from the leaffooted plant bug

 The time is ripe for leaffooted bugs to strike now and cause lots of damage. Stink bugs cause similar problems later in the spring. These pests will penetrate the soft nut and suck out the juicy center of the developing kernel. You can tell they have struck because of the gummy residue left on the outside of the hull.

Sticky substance on the almond hull.

Pest experts say the leaffooted bug could be a problem this season because of high populations spotted last fall and a large survival rate because of the mild winter. Normally, the cold winter temperatures act and an egg parasite act as a natural control by killing off the overwintering leaffooted bug. 

Bug damage inside almond.

From now through May is the prime time to conduct weekly monitoring for the pest. Growers can do this by using a long pole to knock around branches on the upper canopy and watch or listen for the pests to fly around. A clear to light amber sticky substance, called gummosis, found on the hull is a sure sign of their presence – although that means the damage has occurred already. Leaffooted bug damage occurs in March and April while stink bug damage is more common in May and June.

 UC IPM says growers can make sure gummosis is caused by pests by cutting a cross section of the damaged area and then looking for a puncture mark from the bug’s mouthparts. Growers should double check with their pest control advisors when considering treatment and also consider reduced risk materials to protect good bugs that keep almond pests such as spider mites under control during the season.

Growers Prepare for First Alfalfa Harvest of the Season

It has been a race against time for alfalfa growers.

Weevil populations have been on the rise and alfalfa has been growing quickly, spurred by the unseasonably warm temperatures, including that 90 degree weather a week ago.

Field scout Carlos Silva says weevil counts are running 10 to 12 pests for every sweep of his sweep net. Those numbers are climbing closer to the treatment threshold of 18 to 20 bugs per sweep.

Alfalfa growers are nearing the first harvest of the season.

 “Some growers already have treated for weevils,” Carlos points out.

The Egyptian alfalfa weevil poses the most serious threat to the crop, according to University of California IPM. Adult females will insert their eggs in the alfalfa stems. The larvae will hatch and start feeding on the terminal buds and leaflets.

Growers need to focus on managing the pest before the first cutting of the season. UC IPM says: “Weevil management in alfalfa is focused on the period before the first cutting. Control options are insecticides and early harvest. Biological control is not effective at preventing economic damage in most areas because populations of natural enemies are not sufficient to provide control in the spring.”

Alfalfa is cut when the plant is about 24 inches tall.

Right now, alfalfa is about 18 to 20 inches tall – growers usually cut around the 24-inch mark. Carlos anticipates this year’s first alfalfa harvest to start in a week or two.

Meanwhile, cotton growers have been pre-irrigating their fields and starting to purchase their plant seeds.  A number of long-time cotton growers remain committed to the crop, despite the ongoing drought and water availability issues.

Cotton growers have been pre-irrigating their fields.

It’s too early to predict how the prolonged drought will affect cotton acreage this season. Last year, growers planted 213,000 acres of cotton, down 23 percent from 2013, according to the U.S. Department of Agriculture.  Cotton production fell an estimated 24 percent to about 730,000 bales.

Pest Traps Key Tool for Battling NOW in Almonds This Season

Spring officially arrives this Friday. That means it’s time to step up bug watch in almond orchards.

Field scout Jenna Horine has been busy visiting orchards throughout the San Joaquin Valley and setting out traps for navel orangeworm (NOW) monitoring. She should have all in place soon.

Field scout Jenna Horine holds a navel 0rangeworm trap,

These traps play an important role in treatment decisions for the   battle against NOW infestation. Jenna will check the traps, record eggs laid in the traps and rely that information to growers throughout the season.

Long-time almond expert and UC IPM emeritus Walt Bentley has worked with Jenna over the years about the placement locations of traps. Usually, Jenna places traps in three corner locations of an orchard block, depending on prevailing wind direction, nearby fields or orchards when pests may migrate from and grower advice.

The traps are placed about at least five trees from the orchard edge, 6 to 7 feet above the ground, 1 to 3 feet inside a tree drip line and in the shade away from water. As a rule, there never are less than three traps per orchard. For orchards of 20 to 80 acres, UC IPM recommends 1 trap per 10 acres for acres 20 to 80 acres in size. For orchards over 80 acres, the rule is 1 trap for every 20 acres.

Here’s what UC IPM says about using the traps:

• Check twice weekly to determine the bio fix – this is the first of two dates in which egg laying increases in 75 percent of the traps in a given location.
• Record the biofix date.
• Continue monitoring traps, counting and recording egg numbers of a monitoring form. Remove eggs as you monitor.



NOW trap should be 6 to 7 feet above ground.

• Change bait – a mixture of almond meal and almond oil – about every four weeks.

• Look for flat eggs that are laid mostly on the ridges of the trap or on the raised lettering on the top and bottom of the trap. Eggs will be white when first laid but turn orange-red before hatching.
• Graph numbers of eggs laid at each trap reading on the monitoring form. This will give you an idea of when new generations of navel orangeworm are laying eggs.
• Use this information to verify degree-day calculations. If you wish to use this information for timing a hullsplit spray, continue monitoring for the entire season.

Degree-Day Calculations

• Use the biofix determined by egg trap monitoring to start accumulating degree days for following navel orangeworm development and to time hullsplit treatments.
• Egg laying by the second flight of moths is predicted to begin 1056 DD after the biofix.
• Shake trees before third generation egg laying takes place.



Early stage of NOW development.

• If treatments are planned and hullsplit begins before egg laying predicted, apply the hull split spray at the beginning of egg laying. If hull split begins after egg laying is predicted, apply the spray at the beginning of hull split. Back up degree-day predictions by checking egg traps.

Of course, UC IPM officials point out the need to treat for NOW is based on three factors:

• Whether there was significant loss the previous three years.
• The prospects of infestation from nearby orchards, including pistachios.
•  Orchard sanitation, meaning trees had two or less mummy nuts.

Jenna is quick to point out she already can spot troublesome orchards likely to experience NOW problems this season. These are the ones that have had a poor track record in removing mummy nuts.

In one orchard with lax sanitation regularly, for example, Jenna sees lots of mummy nuts that have fallen to the ground. “You can see the worms in the mummies,” she says. It’s going to be another tough year in that orchard.

Drought Part IV: Valley Growers Press Ahead Amid Uncertainly Over Water

It is no surprise we’re headed into a fourth straight dry year and growers are getting quite anxious around the Valley as the prospects of a March Miracle or April showers appear slimmer by the day.

 

State Water surveyor finds a skimpy snowpack in the Sierra.

It also was no surprise that state Department of Water Resources surveyors found dismal conditions last week during their monthly wintertime snowpack measurements in the Sierra Nevada. They reported the water content in the snow was less than an inch, the lowest level since 1991. Even the foot of snow that fell in the high country a week ago won’t make much difference to reverse what is certainly going to be a fourth straight year of drought, water officials say. 

Normally, Mother Nature’s water savings account – the Sierra snowpack – supplies about a third of our water needs. Not this year – again. And, it was no surprise when water managers also last week indicated farmers probably won’t get any federal water for a second year in a row.

As you recall, farmers left acres of fields fallow (an estimated 400,000 to 500,000 acres), uprooted almond trees, turned water well drilling into a booming business and diverted water to more profitable crops. Once again, growers are trying to navigate through these rough waters. 

Alfalfa growers are irrigating for the first time this season.

Growers, however, are a resilient bunch. Despite these challenging times, growers are pressing ahead this season.

Field scout Carlos Silva reports many alfalfa growers are sticking it out again and have been irrigating their crop in the past week. It’s too early to tell how many cuttings they’ll have this season.

Last year, some growers thought they would harvest until early summer, figuring water supplies would go dry by then. Somehow, though, many growers were able to harvest alfalfa until the fall – about the same as a normal season.

For now, the season’s first alfalfa is growing nicely, standing about 8 to 10 inches tall. Carlos plans to start scouting for pests soon.

 Field Day Alert: Here’s a reminder the San Joaquin Sustainable Farming Project’s first event of the year is this Thursday, March 12. Learn about pesticide and pest management issues in almonds, alfalfa cotton at this free event scheduled from 10 a.m. to noon at the Scout Hut, 1910 Marguerite Street, Dos Palos. Our speakers are UC IPM extension advisor Dr. Pete Goodell, state Department of Pesticide Regulation environmental scientist Brandi Martin and Chris Linneman, program manager and engineer with the Westside San Joaquin River Watershed Coalition.  For more information, contact program Director Marcia Gibbs at (530) (530) 370-5325. There should be lots of useful information, especially with another challenging year ahead.