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.