Our Summer Weather Perfect for Cotton ... and Pests

Cotton plant develops first bloom.

You can’t ask for better cotton growing weather.

Our recent daytime temperatures in the Valley have been hovering around the low 90s. Plants are doing well and are in their second position square on the seventh node.

Conditions are perfect – for pests, too.

As growers head into the final critical three weeks for the cotton crop to set this season, I’m seeing increased pressure from lygus and worms. They are migrating from nearby safflower, which are now drying, and from neighboring harvested alfalfa fields. Growers can treat their safflower for lygus as well as leave uncut strips of alfalfa to keep these pests from moving into cotton.

Lygus a threat to cotton.
- Jack Kelly Clark photo

As I scout the cotton fields, I’m collecting in my sweep net as many as 11 adult lygus and nine to 10 lygus nymphs (which feed on the cotton squares). I can’t stress enough the importance of sweeping your fields twice a week so that you can the upper hand on any potential square losses. Check the University of California Statewide Integrated Pest Management online site for more information about lygus and cotton and for treatment thresholds.

When treating your fields, it’s important to select softer products that won’t harm beneficial insects such as green lacewings, big-eyed bugs and ladybugs. Belay and Carbine of some of the good products on the market.

Without natural predators around, you may be opening a Pandora’s box for an outbreak of crop-damaging pests such as aphids. In the end, you could wind up making a second or third pest control application to take care of these problems. That's money you can spend on something else.

Speaking of beneficial bugs, I’m releasing about 5,000 to 10,000 green lacewing eggs per cotton field to help control aphids. A single lacewing larvae can gobble up about 90 aphids a day. Put up the "Hard At Work" sign for these tiny natural pest control workers. 

Here I'm releasing green lacewing eggs in rice hulls on young cotton plants. 

Almond Crop Is Behind, but NOW Development on Time

Walt Bentley, left,  offers some tips at our almond  field day.

Editor’s note: This week, we are featuring a guest blog by UC IPM entomologist Walt Bentley, whose specialty includes managing pests in almonds.

As we all know hullsplit of Nonpareil almonds, the most susceptible cultivar to navel orangeworm (NOW), is almost 2 weeks behind schedule in the central San Joaquin Valley.

  Interestingly, the development of the second generation of NOW is not behind schedule with eggs being laid during the first week of July (see chart below).  This presents an interesting situation.  I believe many of these eggs will result in suicidal emerging larvae, since they will not be able to infest the nutmeat until hullsplit occurs.

NOW's 2nd generation emerging.

 This doesn’t mean we are home free concerning NOW infestation, however.  It points to the importance of timing sprays to the development of the susceptible stage of the nut (initiation to 5 percent hullsplit). Such timing will optimize the effects of any insecticide applied with the residual remaining through the complete second generation egg laying.  I believe a good portion of the early second generation eggs will hatch and be unable to infest the nut.  The remainder of the generation, that can reach the nutmeat, will be shorter in time duration than normal.  If sprays are timed correctly, excellent chemical control should be achieved. 

Hullsplit is behind schedule in the Valley.

The same scenario that could optimize control of NOW in Nonpareils may result in making later splitting varieties such as Carmel, Sonora and Price more susceptible.  This is a scenario that we see from time to time.  Here the third generation eggs may be timed to Carmel hullspit, resulting a greater potential for infestation.  So, try to focus on early harvest of any late soft shell variety. It may still be a good idea to monitor egg traps to see how NOW egg laying coincides with the hullsplit of these later soft shell varieties.  This can give you an idea if additional chemical control may be needed.

Walt Bentley is a long-time entomologist with the University of California Statewide Integrated Pest Management program at the Kearney Ag Center in Parlier.

The Envelope Please: Alfalfa Growers' BMPs an Award Winner

If there were a Best Management Practices Award in farming, I would surely nominate some of our local alfalfa growers. With cotton entering an important period of plant development, growers are doing a good job trying to keep pests from migrating from alfalfa to neighboring cotton fields.

I’m seeing lots of strips of uncut alfalfa during my travels throughout the Valley. These strips are acting as homes for lygus, armyworms and alfalfa caterpillars and keep these pests away from cotton. At the same time, some growers are treating the strips for the pests. Kudos to these growers and here’s my BMP Award to them.

For a short refresher course, check out the University of California Statewide Integrated Pest Management Program’s online site about managing alfalfa and lygus.

Right now, growers are either on their fifth or sixth cutting of alfalfa. The triple-digit heat is affecting the quality of the crop. The Farmer’s Almanac says the Valley temperatures average around 94 degrees this time of year. Since the unusual rainstorm we had at the end of June, we’ve had multiple days above 100 degrees.

To deal with the quality issues and hot weather, growers are adding a little nitrogen to help push the crop and help the alfalfa grow a little faster. Keep following those BMPs, stay cool and remember your hat and sunscreen.

Critical Time to Invest in Managing Cotton Crop

I'm checking in with growers at our field day.

Dan Munk stresses importance of plant monitoring.

Can we declare California cotton the comeback commodity of 2011? When global prices sagged and water became a precious commodity during the height of the drought, some started to write the obituary for the state's cotton industry.

With apologies to Mark Twain, the reports of cotton’s death have been greatly exaggerated. While local growers and pest control advisors attended our Cotton Pest Management Field day last week, the National Agricultural Statistic Services was reporting planted cotton acreage in California this year surged to 450,000 acres, up 47.1 percent from last year. Pima planted acreage rose 44.4 percent to 260,000 acres while acala acreage increased 52.2 percent to 190,000 acres.

Growers are investing a lot in cotton this season. With everyone talking about a short season because of the unseasonable weather this year (including the weird summer rainfall last week), these next five to six weeks will be critical for setting the cotton crop. To assist growers through this important period, our Field Day experts offered these tips and observations:

Dr. Pete Goodell, University of California Statewide Integrated Pest Management advisor, Kearney Ag Center: In many cases in the northern San Joaquin Valley, there is a pretty good set going on. Lygus is going to be the primary threat to setting the crop. There are three things growers should do:

1 – Ask what are the potential sources for lygus.

2 – If you have lygus in your field, be vigilant about monitoring the fields to ensure you can detect them and carefully evaluate whether the populations collected in your sweep net are actually a damaging population.

3 – If you need to treat the fields, rotate your materials to avoid insecticide resistance and start with softer materials first. These materials will protect as many beneficial insects as possible and help you avoid outbreaks of aphids or spider mites.

We are behind this year, but if we get a warm October without rain then we will be able to enjoy an extended season. But if the season ends at the normal time, then it’s going to be a short season, which translates into a short crop.  Right now is the time to invest in getting a good set going. Go out and look at your crop. Don’t panic. For those with alfalfa nearby, leave alfalfa strips wherever you can during your next two cuts this month to protect your cotton fields from lygus.

Dan Munk, Cotton Specialist, UC Cooperative Extension farm advisor in Fresno County: With talk about the late development of the crop, growers should be realistic and adjust their practices with the expectation of a lower yield, particularly pima, which requires a longer season. Growers should scale back some nutrient applications to reflect those lower yield expectations.

Fusarium race 4 is a very serious issue. (The disease will causes cotyledons and leaves in young plants to wilt and drop. Certain pima varieties are the most severely affected.) During the season, there is not a lot you can do about it. To manage it, growers need to first recognize they have a problem, identify where it is in the field and take steps to contain it. The best tool for dealing with Fusarium race 4 for next season is using varieties that have a high tolerance for the disease. In the past five to six weeks, I have seen significant plant die back and presence of the disease in Fresno County. Call a farm advisor for a field visit if you suspect any problems. More information about the disease is available from UC IPM.

Bob Hutmacher, UC Statewide cotton specialist: Fusarium race 4 has spread over the past seven or eight years. Growers in the southern part of the Valley have dealt with the disease the longest. More growers are becoming educated and aware about the disease. The problem is caused by soil inhabiting fungal organisms that can survive in the soil for years. It is a long-term management issue for growers as they consider options to contain its spread. They are learning how to identify the disease and select resistance varieties.

Weathering This Unusual Growing Season: Field Days Offer Answers

Record-setting rainfall is the talk of the Valley as we continue to see some wild weather and yo-yoing temperatures. It’s turning out to be a short season for cotton growers. How should growers approach their crop this summer?. Well, there will several opportunities in the coming week to ask questions and learn what to do this season from top cotton experts.

On Thursday, I will participate in our Cotton Pest Management Field Day from 10 a.m. to noon at the Bettencourt Farm in Mendota. The featured speakers: Dr. Pete Goodell of University of California Statewide Integrated Pest Management at the Kearney Ag Center on managing lygus and Dan Munk, UC Cooperative Extension farm advisor and cotton specialist, on plant development and its role in IPM. Check our Sustainable Cotton Project website for directions.

 The following week on Wednesday July 6, there will be two Cotton Production Meetings focusing on making realistic crop, nitrogen and water management decisions in a short season. Growers can attend either one. The presenters include Dan Munk, UC Statewide cotton specialist Bob Hutmacher, UCCE Tulare and Kings counties farm advisor Steve Wright and UC extension entomologist Larry Godfrey.

The first session will be from 8 to 9:15 a.m. at the Comfort Inn, 10 N. Irwin St., Hanford. Breakfast and registration begins at 7:15 a.m.

The second session will be from 10:30 a.m. to noon at the West Side Research and Education Center, 17353 W. Oakland Ave., Five Points. A lunch will follow. For more information, call Steve Wright (559) 684-3315 or Dan Munk (559) 456-7561.

Bring your questions to these free events. See you there.

Cotton: The Case of the Missing First Squares

As I travel around the Valley, I’ve been noticing an unusual trend in many cotton fields.

The plants are at the seventh or eighth node, or true leaf, and showing the first pinhead squares. In all my years of scouting, though, I’ve never found so many first squares missing on young cotton plants. The first square location is important and can impact profits in the long run.  Losing the first square position causes the plant to become more vegetative and experience problems retaining fruit.

   I’m seeing missing first squares in 20 to 30 percent of the cotton fields that I’m scouting this season. In the past, the highest rate 5 to 10 percent of the fields.

   The squares are nibbled off by pests we had this spring. The growing      season is eight to 10 days behind schedule.

   Some growers irrigated too soon and ended up lowering the soil     temperature, which affected plant development. UC IPM is a good resource to learn about monitoring early squaring in cotton growth and development.

   Of course, this plant condition is worrisome to growers. Some might be tempted to apply growth regulators such as Pix, which are designed to increase boll retention and cut back vegetative growth.  Regulators can reduce yields if applied when plants are going through stressful, especially moisture-related, conditions. They also can lead to stunted plants, which could prompt growers to increase nitrogen into the soil to help the plants grow taller for easier harvest in the fall.

Determine the reasons why the first squares are missing. Some pest control advisors might want to start treating for lygus now.

Remember to keep monitoring the fields for pest pressures and be familiar with the surrounding fields. If you’re growing safflower nearby, you might want to treat it for lygus. If you have alfalfa, let borders or strips to prevent migration of worms and lygus. You could treat the alfalfa strips rather than the cotton field.

Lacewings are natural enemy to aphids.

Meanwhile, I’ve spotted some aphids in the cotton fields. Natural predators such as ladybugs and lacewings could take care of small problems. Spot treatment is another alternative.

I am starting a weekly release of 10,000 to 15,000 lacewings for each field I’m scouting to control the aphids.

Field Day Alert: I will participate in our Cotton Pest Management Field Day on Thursday, June 30 from 10 a.m. to noon at the Bettencourt Farm in Mendota. The featured speakers: Dr. Pete Goodell of University of California Statewide Integrated Pest Management at the Kearney Ag Center on managing lygus and Dan Munk, UC Cooperative Extension farm advisor and cotton specialist, on plant development and its role in IPM. Check our Sustainable Cotton Project website for directions. It’s sure to be extremely informative and give growers an opportunity to meet cotton experts directly.

                        

Butterflies a Warning Sign for Alfalfa Growers

Alfalfa caterpillar butterflies.

Photo buffs might get a thrill taking snapshots of colorful yellow and white butterflies fluttering around amber fields of alfalfa.

Growers, though, might get a chill when they spot dozens of these insects in their fields. It’s a warning sign that alfalfa caterpillar populations are on the rise.

Sweep the net in a 180-degree arc.

With summer around the corner, I’m starting to see an increase in worms around Valley alfalfa fields as growers prepare to cut their crop for the third time this season. If left unchecked, caterpillars and armyworms can eat away a grower’s profits as they feed on leaves and stems and defoliate the crop.

I can’t stress it enough: Monitoring your fields pays off. It’s a smart way to manage pest threats effectively and economically while helping you determine when to schedule treatment. In the long run, you avoid unnecessary treatments and save money because your decisions are based on need instead of the calendar.

 As soon as caterpillars are spotted in the field, you can use this as a warning sign and begin regular sweeping for alfalfa caterpillars, western yellowstriped armyworms and beet armyworms. 

To make the task easier, the University of California Statewide Integrated Pest Management program offers a monitoring form (100 kb pdf) to record your observations and tips about sampling with a sweep net. The monitoring form includes treatment thresholds.

Here’s a summary of alfalfa caterpillar and armyworm monitoring guidelines from UC IPM: With a sweep net 15 inches in diameter, you should take weekly samples in fields where plants are at least plants 6- to 10-inches tall. Divide each field into four sections and take five sweeps per area – for a total of 20 sweeps. Lets confirm that these are taken from the site correctly.

Western yellowstriped armyworm larva.

After finishing your sweeps, identify, count and record the number of healthy and parasitized caterpillars (caterpillars with fatal parasitic wasps living in them) caught in the net. Then you divide the total by the number of sweeps. Use the monitoring form to list the average number per sweep. Here’s how you determine a parasitized caterpillar: Pull apart young worms (at least a half-inch long) and see if a white or green parasitic wasp larvae comes out. Population estimates are based on the average taken in a field, counting only armyworms that are at least a half-inch long.

Full-grown alfalfa caterpillar.
UC IPM photos by Jack Kelly Clark

If you’re not scheduled to cut soon after monitoring, you should follow these guidelines for scheduling treatment:

• An average of 10 or more nonparasitized alfalfa caterpillars per sweep.
• An average of 15 or more nonparasitized armyworms per sweep.
• An average of a combined 10 or more nonparasitized alfalfa caterpillars and armyworms per sweep.

Be sure to talk to your pest control advisor about organic and or targeted reduced risk materials that won’t harm beneficial insects or the environment.