Cotton Growers Still Grappling with Nasty Soil Disease

Over the years, Bob Hutmacher has visited countless cotton fields across the Valley.

He’ll field a call from a grower asking him to come check out a problem with the crop.

“ I feel like the grim reaper when I walk into a field and they ask if they have Race 4 fusarium wilt,” he jokes. 

This season, the University of California Cooperative extension specialist at the Westside Extension and Research Center has visited 10 cotton fields and found they have lost 5 to 15 percent of their stands due to the soil disease.

UCCE cotton expert Bob Hutmacher

“It’s going to be a continuing battle. It’s difficult to contain,” he told growers attending a recent cotton field day in Mendota. Identified in 2001 in Fresno-Kings counties area, the nasty soil disease was identified in four different locations in the San Joaquin Valley within three years. It has steadily spread northward to the upper San Joaquin Valley. 

Recently, Race 4 fusarium was discovered in West Texas cotton fields around the El Paso region. Hutmacher suspects it could be infecting fields in Arizona – although nothing has been confirmed by agriculture officials.

Race 4 is a fungus in the soil. It can infect plants and cause a vascular wilt in a number of cotton varieties. The spores can be spread through regular farming practices such as irrigation and cultivation.  It can cause damage in a variety of soil types. Over time, it can spread through an entire field and ultimately cause widespread plant losses and stunted growth, adding up to a costly loss in yield.

“It could be a couple years when you detect anything or it could be 10 years.”

Hutmacher says seed companies have developed resistant cotton seed varieties and continue to look for improvements. Researchers in California and Texas are exploring crop rotation practices that could limit the spread of the disease.

Race 4 fusarium will wipe out sections of cotton plants.

In the 10 fields Hutchmacher inspected this season, about half of them were in the second or third season in cotton. Some of the worst cases, though, were in fields planted in melons or tomatoes the previous year.

“We still don’t know of a crop rotation that knocks down its survival,” he says. However, the disease appears to be controlled the year after the field has been left fallow the previous summer. “That actually knocks down the problem.”

Hutmacher says public research institutions, government ag agencies and private ag firms need to continue working together to come up with a solution. 

Cotton plants will wilt and die from the soil disease.

“Until you get a perfect resistant variety, the solution is a really resistant cultivar along with a kind of chemical treatment that is affordable. That will reduce down the infection rate. I don’t think it will need to be perfect,” he says. 

Hutmacher urges growers to contact UC farm advisors if they see any problems in their fields.

Once growers know they have an infected field, they can take steps to slow the spread of the disease. That includes cleaning soil from equipment, limiting the movement of soil and plant debris from the infected field and planting resistant varieties.

“People have been very good about working with their PCAs, seed companies and consultants to try to get answers to know what they are dealing with,” he says.

It’s Time to Get Shakin’ in Valley Almond Orchards

With September around the corner, it’s time to shake, dry and sweep in Valley almond orchards.

Field scout Jenna Mayfield says the almond harvest is finally picking up after getting off to a slow start this season. “Growers are shaking away, knocking the nuts off the trees.” 

Shakers use big claws to grasp on the tree trunk.

Almonds are havested by mechanical shakers outfitted with crab-like claws that clamp onto the trunk of the tree and vigorously shake the almonds onto the grounds.

Jenna notes growers plant at least two different varieties of almonds for cross pollination and each variety will mature at a different time. That means growers will send the harvesting equipment to shake the mature nuts off the trees again. After the nuts are collected off the ground, they are taken to a processor to remove the dried green hulls, crack the shells and separate the meat.

Sometimes, there will be a third shaking if growers believe there are enough left over nuts to make it economical to harvest again. It’s quite a juggling act for growers, especially small farms that need to schedule outside harvesters to bring their equipment into the orchards.

After shaking, the almonds will dry on the orchard floor.

You might call the almond harvest a marathon rather than a sprint. This year, though, growers may wind up sprinting near the end of the harvest. Here’s why: Jenna points out that some growers started the almond harvest as early as July 22 in 2017. This year, the earlybirds began around August 10.

The nearly three-week difference could push the harvest into Halloween or even later for some. That could make it tricky if the weather changes and wet storms hit the area. Rain will hurt the quality of the meat and run up costs for mechanical drying. Jenna says the threat of rain could trigger around-the-clock harvesting.

Another worry for growers: Ants. The longer the nuts are on the ground the more susceptible they are to ant damage. “Growers need to be vigilant about ants.”

Growers worry about ants damaging almonds on the ground.

At the same time, growers are mindful of air quality and are investing in equipment to keep dust down during shaking and sweeping operations. Farm advisers recommend growers adjust harvest equipment to match orchard conditions, following simple steps such as reducing speed or planning the machine’s path up and down the rows between trees.

Growers try to minimize dust during the mechanical harvest.

As a rule, growers will shake about two weeks after the last irrigation to minimize bark damage during the shaking. The timing depends on the type of soil. Sand requires less time to dry out while clay requires more time.

In orchards with sand and other soils that don’t hold water very well, growers may need to irrigate between harvesting the different varieties.  Proper water management is important during harvest time.

Yes, the harvest may have started, but it’s a long way to the finish line.

 Happy shaking.

Growers Reining in Cotton’s Heat-Fueled Growth Spurt

It’s no secret cotton thrives in heat. That’s one reason you see the fiber grown in the South, Southwest and, of course, California’s great Valley.

“Cotton originated in hot, dry regions and prefers those conditions to achieve maximum production,” says Australia’s Division of Agricultural Services. “Cotton therefore does best in areas with a long, hot season. The higher the average temperature (within reason), the faster cotton will grow and develop.”

Moreover, the growth of cotton plants will follow a predictable pattern under favorable moisture and temperature conditions. Growers can chart development by charting daily temperatures to monitor the plant’s progress.

For the Valley this summer, the average temperature has beyond what the Aussie Ag folks would describe as “within reason.”

As mentioned in last week’s post, the Valley has experienced a record-breaking July for consecutive 100-degree days in the region. While we had a number of days in the high 90s this month, the average high for August so far is 101 degrees, according to the National Weather Service.

Excessive heat could impact cotton bolls.

Researchers say cotton yield and quality can be affected by periods of extreme heat and create heat stress. The result could be the shedding of bolls, excessive vegetative growth or reduction in fiber quality because of problems in boll development.

“Cotton plants can grow three inches a day when it’s 100 degrees or more during the day,” field scout Damien Jelen says. “Growers have been treating their fields with plant growth regulators.”

Growers can experience production problems if their plants grow too much – which in industry parlance is called “excessive vegetative growth.”  This condition can lead to delayed maturity, boll rot and problems during harvest. If the plants grow too tall, the open bolls would be out of the reach for the harvesters collect the fiber, Damien says. We’ll have to see how many more Hot August Days and Nights are in store the rest of this month.

Worm counts are up in alfalfa fields.

 



Meanwhile on the pest front, Damien says aphid and worm counts are on the upswing while lygus numbers are under control. He says some alfalfa growers are treating their fields for worms.

In almonds, the harvest continues to be off to a slow start, according to field scout Jenna Mayfield. Activity has been less than robust for this time of the year. Jenna anticipates tree shaking to pick up this week.

Excessive Valley Heat Poses Challenge for Almond Harvest

No one needs to tell Valley farmers it’s been very hot, even by local standards.

The Fresno region set a record for the most consecutive days of 100-degree temperatures in July. In fact, everyone endured 30 straight days of triple-digit weather until the high temperature fell to a cool 99 degrees on August 5.

Almond field scout Jenna Mayfield adds there has been little relief at night with the lows hovering in the 70s this past month. “We haven’t had a break. We welcome the days when it’s in the 90s,” she says. Jenna adds:  “The air is so unhealthy. There’s smoke from the wildfires. It’s hard to breathe.”

NASA photo shows smoke covering the Central Valley.

Add in smoke and hot weather and “it makes you more tired. “It’s hard on workers in the fields,” Jenna says. “They’re toughing it out.”

Jenna says the excessive heat may be affecting the pests as well. “The mite pressure is down in almonds. Navel orangeworm numbers are low.”

Jenna thinks the heat coupled with the addition of miticides in the hull split sprays are keeping mites down. Mite populations usually explode during the hot summer days.

Right now, growers are moving around harvesting equipment and a few have started shaking nuts off the trees. Harvesting should begin picking up this week.

“Everything has been slow. We really haven’t seen much harvesting yet,” Jenna says. The prolonged heat spell prompted growers to figure out the best strategy to irrigate during hull split and prior to harvest.

More growers should start harvesting almonds this week.

Extreme heat triggers more evaporation and dry ground heats up more quickly than wet soil.
Here’s the quandary: If growers irrigate too much, they increase the risk of diseases, shaker damage and delayed harvest. If they don’t provide enough water, the trees become over stressed, mite activity could explode and kernel weights might decrease. “It’s a balancing act,” Jenna says.

Pomologist David Doll of UC Cooperative Extension in Merced County advises growers to maintain the same frequency of irrigation during hull split but make adjustments during irrigation sets.

“Reductions to irrigation (i.e. 50 percent at the onset of hull split) to apply a stress can be made by reducing the duration. Trees should be monitored by either a pressure chamber or observations (i.e. wilting) to identify stress levels. If the trees are over/under-stressed at the end of the cycle, adjust the duration,” he writes in his Almond Doctor column.

Here are some recommendations at this time:

·         Pre-Harvest week: 20-50 percent reduction to help begin a slight dry down of the orchard.
Harvest week: 30-50 percent evapotranspiration (ET) – some water should be applied, but with enough time to allow orchard floor drying for shaker movement.

·         Post Harvest: 100 percent ET – stress should be minimized at this stage as the tree prepares for next year.

Growers need to adjust irrigation schedules during harvest.

“The recommendations are made for micro, drip, or solid-set irrigation systems, but the recommendations would be very difficult to achieve using flood irrigation,” Doll writes. “With flood irrigation, growers will want to adjust their irrigations so that some trees show signs of water stress between irrigations during hull split, and harvest will be delayed until the wettest part of the field is dry. Increasing distribution uniformity by taking into account soil differences with different checks may help with a uniform harvest.”