Going Beyond the Hype of Soil Health in the Central Valley

For farmers, two crucial elements for growing successful crops are water and a good, healthy soil.

Rain, of course, ensures we have enough water to irrigate the crops. On the other hand, what keeps the soil healthy is subject to debate, according to Jeff Mitchell, associate vegetable crop specialist at the Kearney Ag Center.

During a cotton field day last month in Mendota, Mitchell encouraged growers to go beyond the hype about soil health and pointed out that they could do something about it.

“The reason we have such good levels of productivity is we have water. We have the luxury of developed water through the Central Valley Project. That has enabled people to mask a lot of problems.”

Conventional tillage is widely practiced by Valley growers.

Mitchells says farmers have routinely followed the same practices from year to year to prepare the ground for the next season’s crop. Tillage – preparing the soil using mechanical means such as a tractor to turn over the ground – is the common practice in the Valley. 

“Water and tillage have masked a lot of problems,” he said.

Studies have reported tillage causes soil erosion. In hilly areas, the eroded soil moves downslope. On flatlands, the eroded soil can fill drainage ditches.

A 2003 study by the USDA Agricultural Research Service in Minnesota found the tillage erosion loss of 27 tons per acre per year was almost 5½ times more than the natural 5 tons per acre loss per year.

“What constitutes good soil management?” Mitchell asked growers. “Diversity, organic matter and keeping the ground covered.”

“Mother Nature doesn’t do tillage,” he said.

Mitchell said planting a winter cover crop will boost soil health. “This is not new stuff,” he said, noting discussions about cover crops in the Valley have been around for a century. “This is coming back to basic principles.” 

Here is a field with a legume cover crop.

The benefits of cover crops include: Slowing erosion, improving soil health, enhancing water infiltration, smothering weeds, controlling pests and diseases and increasing biodiversity.

The challenge, he added, is “nobody is going to do cover crops without irrigation.”

During the first half of the 20^th century, farmers planted cover crops extensively. But in the 1950s, growers moved away from this practice because of the development of  pre- and post-emergent herbicides. But this is changing with concerns about chemical inputs into the soil.

A tractor is rolling a vetch no-till cover crop.

From 1999 through 2014, Mitchell and other researchers quantified cover crop biomass production for a variety of mixtures under winter rainfall and limited supplemental irrigation.  The group conducted a separate study to determine changes in soil water storage under three cover crop mixtures compared to fallowed plots during the winter of 2013 and 2014 to investigate tradeoffs associated with water use by cover crops in the region.

“ From this long-term systems research, we conclude that while vigorous growth of winter cover crops in the Central Valley may not be possible in all years due to low and erratic precipitation patterns, there may be benefits in terms of providing ground cover, residue, and photosynthetic energy capture in many years. However, cover crop biomass production may come at a cost of soil water depletion in this semiarid, drought-prone region,’’ the study said.

A Texas NRCS soil demo of no-till and tillage in water.

Mitchell brought pans of  till and no-till soil samples to illustrate his point. He dropped a clogfrom each sample into a separate cylinder filled with water. The convention tillage sample started to disintegrate immediately, representing sediment going downstream. The no-till soil soaked up the water and only small particles gradually dropped into the water.

What’s this mean? “Better water holding capacity (with the no-till soil),” one farmer responded.

To view Jeff’s presentation, you can go to our website and see for yourself just how different the two soil samples were. The link is http://www.sustainablecotton.org/videos/index/115.

Holy Cow – Worm Population Surges in Alfalfa Field

Damien Jelen walked into a sun-baked alfalfa field, swinging his sweep net to the left and then to the right. Swoosh. Swoosh. Swoosh. Swoosh.
 

Beet arrmyworm. (UC IPM photo)

He opened up the net, revealing dozens of squirming worms. “The numbers are bumping up,” Damien says, citing this month’s relentless heat wave as one reason for the population explosion.

Yes, it has been extremely hot in the Valley. As July nears a close, all but three days this month have recorded triple-digit high temperatures, averaging a sizzling 102 degrees – hot even by Valley standards. Historically, the average high for the month is 98.4 degrees.

Since late spring, field scouts and growers have been on the lookout for beet armyworm, western yellowstriped armyworm and alfalfa caterpillars. Yellow and white butterflies flying around the fields are telltale signs alfalfa caterpillars are on the upswing.

Alfalfa pests can significantly reduce yields, stand life and forage quality.  Alfalfa serves as an important food for the state’s $6 billion dairy industry.

Western yellowstriped armyworm butterfliers.

Armyworms leave foilage looking like skeletons while alfalfa caterpillars will gobble entire leaves. Most of the time natural enemies such as bigeyed bugs and lacewings are plentiful enough to keep these pests at bay. Or other growers may opt to cut their crop a little early.

But with two or more months of harvesting still left in the season, some growers are spending the money to treat their fields. “They had to spray. They can’t wait,” Damien says.The pest counts were above the treatment threshold.

Alfalfa caterpillar. (UC IPM photo)

During the summer, UC IPM recommends scouting a field two to three times a week. To come up with good pest counts, UC suggests dividing each field into four sections and taking five sweeps per section for a total of 20 sweeps.
 “See if white or green parasitic wasp larvae are inside. Base your population estimates on the average of all sweeps taken in that field, counting only those armyworms collected in sweeps that are at least 0.5 inches in length,” UC IPM says.

Growers should consider treating their fields under these thresholds:

• 10 or more nonparasitized alfalfa caterpillars per sweep,
• 15 or more nonparasitized armyworms per sweep, or
• 10 or more nonparasitized alfalfa caterpillars and armyworms combined per sweep.

FIELD DAY: If you want to learn more about latest

 trends in alfalfa field and pest management and pesticide regulations, come to Tuesday’s Alfalfa Field Day in Firebaugh. The free event will be from 9:30 a.m. to 12:30 p.m. at the Firebaugh-Mendota United Methodist Church, 1660 O Street, Firebaugh. Featured speakers are:

•          Lynn M. Sosnoskie, agronomy and weed science advisor, for the University of California Cooperative Extension in Merced and Madera counties, who will discuss weed control in alfalfa and the chemical, cultural and biological factors that can affect success and failure.
•      Tom Casey, pest control operations official for the Fresno County Agricultural Commissioner’s Office, who will cover current pesticide use and regulations.
•        Nicolas Clark, agronomy and nutrient management advisor at UCCE Kings, Tulare and Fresno counties, who will offer tips about insect pest management in San Joaquin Valley alfalfa hay.

Continuing education credits have been approved and include one hour of regulations. The field day issponsored by the San Joaquin Sustainable Farming Project, which provides farmers with valuable strategies to improve yields while becoming better environmental stewards in today’s challenging economic and regulatory climate. For more information about the field day, contact Project Director Marcia Gibbs at (530) 370-5325.

Mapping Out Cotton Growth Can Avoid Disappointment at Harvest Time in the Fall

Drive around the cotton fields in the Valley and you will notice each field looks a little different.

In some fields, the plants may have eight fruiting branches. In others, the plants may be seem smaller with fewer fruiting branches.

Yes, every cotton field develops at a different rate. Field scout Damien Jelen sees it every day ashe visits fields throughout the region.

For cotton growers, charting the progress of their plants is an important practice that can make a difference in yield and profit.

Cotton experts encourage growers to do plant mapping, which serves a guide for evaluating the crop’s health during the season.

Charting cotton plant's development can improve yield.

Taking regular measurements and comparing them to growth guidelines will let growers know how the crop stands – whether it is doing well or under stress because of pests, diseases or lack of water. By knowing the status, growers can take proactive steps to add fertilizer or plant growth regulators, when to time pesticide or herbicide applications, manage irrigation and identify fruiting problems.

At the moment, plants are around their 12th and 13th nodes, according to Damien.  The first bloom has occurred in many fields. “The plants are about three feet tall,” he says. 

Plant monitoring during early squaring lets growers assess plant vigor and square retention. They should measure for plant height, the number of main stem nodes and the first position squares on the terminal five fruiting branches. Generally, a square retention rate of 80 percent or higher is ideal for going into bloom.

If retention drops, growers might opt to use growth regulators to enhance development. They should check with their pest control advisor or local University of California farm advisor before making any application.

Here’s one simple method to follow. The cotton season can be divided into four management periods:

·         From plant emergence to square: This is when you count plant stand and height and the number of nodes. Walk around the field and check for drainage issues, missing rows and pest damage. This information will help with replanting and pest management decisions.

·         From firstsquare to first bloom: In this stage, sample at least five plants in four different sections of the field. Then collect information about plant height, the number of nodes, fruiting branches and square retention. Also record fruit set and growth. This information is important for crunching numbers and guiding decisions on pest control and the possible use of growth regulators. For example, square retention calculations can assist in developing pest management strategies.

·         From first bloom to cut-out: This is the time when the plant becomes larger. You record plant height, number of nodes, nodes above first position white flower and first position squares above the white flower and first position bolls below white flower in the first or second position. This information indicates how the crop is developing and provides insights about vegetative growth and boll development as you approach cut-out – the final stage of plant growth before the bolls open.

·         From Cut-out to defoliation:Measure the plants for boll retention, boll regrowth and boll opening. Noting nodes above cracked boll will help with the decision about the timing of defoliation.

UC IPM offers a wealth of information and tools for cotton growersthe sitemonitoring cotton plant growth.

FIELD DAYS: A trio of University of California extension and farm advisors willoffer tips and provide the latest developments in cotton across in the San Joaquin Valley during a field day tomorrow in Mendota. Open to all growers and pest control advisors, the free event starts at 9:30a.m. atPik-A-Lok Farms on Bass Avenue in Mendota. Featured speakers are:Dan Munk, UCCE Fresno County farm advisor and cotton specialist, who will discuss monitoring cotton for improved yield performance. Bob Hutmacher, UCCE extension specialist of the Westside Research and Extension Center, who will provide an update cotton diseases and plant development issues. Jeff Mitchell, associate vegetable crop specialist at the Kearney Ag Center, will talk about going beyond the hype of soil health and doing someth

ing about it.

On Tuesday, July 31: UC extension advisors and a county official will update farmers about the latest trends in alfalfa field and pest management and pesticide regulations during a field day in Firebaugh. The event will be from 10 a.m. to 12:30 p.m. at the Firebaugh-Mendota United Methodist Church, 1660 O Street, Firebaugh. Featured speakers are:

·         Lynn M. Sosnoskie, agronomy and weed science advisor, for the University of California Cooperative Extension in Merced and Madera counties, who will discuss weed control in alfalfa and the chemical, cultural and biological factors that can affect success and failure.

·         Tom Casey, pest control operations official for the Fresno County Agricultural Commissioner’s Office, who will cover current pesticide use and regulations.

·         Nicolas Clark, agronomy and nutrient management advisor at UCCE Kings, Tulare and Fresno counties, who will offer tips about insect pest management in San Joaquin Valley alfalfa hay.

Continuing education credits have been approved and include one hour of regulations. The two field days are sponsored by the San Joaquin Sustainable Farming Project, which provides farmers with valuable strategies to improve yields while becoming better environmental stewards in today’s challenging economic and regulatory climate. For more information about the field days, contact Project Director Marcia Gibbs at (530) 370-5325.

Hot, Humid Weather Worrisome for Almond Growers

Bing… A short text message arrived on field scout Jenna Mayfield’s cell phone, reading “Hulls stopped splitting!”

The almond grower’s text was rather tongue-and-check, yet insightful at the same time. It appeared a build-up of hot, humid weather over the several days last week seem to slow hull split in his orchard.

Adding to grower anxiety, a few summer showers fell in parts of the Valley last Thursday night, cranking up humility levels as the daily high temperature reached the 100s. “We usually get this kind of humidity in September. To have it in July is definitely not normal.”

Humid weather and sprinkles worried growers.

Weather experts blamed monsoon moisture coming from the Arizona area for bringing the Hawaii-like humidity to the Valley and Northern California.  Yes, it was unusual to see lots of clouds in the sky on Friday and a higher-than-normal humidity during the mid-afternoon.

“Almonds grow best when we have super dry climate,” Jenna points out. “If the humidity continues it could be a problem. It may slow hull split.” But forecasters say continued triple-digit temperatures and drier afternoons are on tap this week, easing the minds of many almond growers.

Still, Jenna says some growers are hedging their bets and adding fungicides to their hull split sprays for navel orangeworm.  Growers already were adding miticides to their hull split sprays.

Yes humidity in orchards can lead to foliar diseases such as alternaria leaf spot. The symptoms are large brown leaf spots that turn black as the fungus spreads on the leaf surface. The leaf spots develop quickly in July and potentially can cause defoliation. 

Orchard humidity also can trigger rust and scab, which is a relative of alertnaria. These two diseases also can cause defoliation and weaken trees, impacting future almond production.

Humidity can trigger alternaria leaf spot. (UC IPM photo)

Meanwhile, field scout Damien Jelen says bug pressure has dropped in cotton, which is good news after a recent uptick in crop-threatening lygus bugs. During his field visits, Damien snared an average of one to two lygus for every 50 passes of his sweep net. The results about normal for lygus this time of year.

Growers are leaving uncut strips of alfalfa near cotton fields.

Damien says alfalfa growers with fields near cotton have been doing a good job leaving uncut strips of alfalfa during recent cuttings. These strips create habitats for lygus to stay in alfalfa during harvest rather than migrate to cotton.

 

The worm counts are high in alfalfa. But growers appear to be holding off treatment, reasoning the worms issue dissipates after each cutting.  Damien advises growers to remain vigilant about pest issues in alfalfa.