Determining the Ideal Time to Get Cracking on Defoliating Your Cotton Crop

 At the start of the month, some pest control advisors in Fresno and Merced counties predicted in the AgFax.com crop advisory newsletter that local cotton growers would start defoliating their crop around the start of this week – the first full week of fall.

A warning sign alerts people defoliation has taken place.

Well, as it turns out, some growers beat that prediction last week and got an early jump on defoliation before summer’s end – even though they may have been able to wait a little longer to allow more fruit to mature. Indeed, the early varieties of acala I’ve seen in the fields are at around six to seven nodes above cracked boll (NACB).

Remember, NACB is used as a guide to help growers determine the right time to apply defoliants. The University of California Integrated Pest Management program says the “ideal timing for defoliation is when unopened harvestable bolls are an average of four or less nodes (including missing branches) above the highest first position cracked boll.”

As a rule, plant maturity is the most important factor in making the final decision. The goal is to determine when the boll population will lead to a significant yield and the optimum time for harvesting the bolls. Here is the University of California Integrated Pest Management link that covers scheduling defoliation.

Here's a field about 12 hours after defoliants were applied.

Why defoliate a little early? There are many reasons. Some growers do it because the aphid and whitefly population are threatening the crop. My guess here is a few growers decided to sacrifice a little yield in order to get a head start on harvesting so they can in their crop sooner than later, thus avoiding potential issues such as early season rain.

But I see advantages for holding off with defoliation and allowing more fruit to mature. Right now, aphid pressure has subsided and treatments are down from earlier this month. Whitefly counts have decreased as well. Those are good signs because it reduces the threat of developing sticky cotton. We do have extra time to play with this season. By my estimates, the cotton season is about seven to 10 days ahead of normal for this time of year.

Meanwhile in almonds, our field scout Jenna Horine reports all growers are finally shaking the nuts off the trees. Nonpareils are pretty much off the ground. Other varieties remain in various stages of harvest.

Almonds are drying on the ground.

As she scouts the orchards, Jenna has been picking up a few nuts off the ground and cracking them open. From these spot checks, she is finding these random samples to be pretty clean, or free of pests. She’ll be checking all her orchard samples later to get a thorough look for any the evidence of pests in the nuts. We’re report on her findings after crack-out.

Overall, she has not found any major pest issues this season. Our hats off to growers for following good pest management practices. “It’s all about preventative measures,” Jenna says.

 

Cotton tour participants get a chance to pick some cotton.

The annual Cotton Tour is less than a month away. This popular free event is a rare opportunity to get an inside look at cotton production – from the field to the gin. Set for Friday, October 19 from 8:30 a.m. to 5 p.m., the tour begins at the Best Western Apricot Inn at Interstate 5 and West Panoche Road, about 23 miles southwest of Firebaugh. Go to the Sustainable Cotton Project website  to reserve a spot. Visit with growers and meet leading cotton experts. 

Cotton Growers Tackle Pests to Stay Out of Sticky Situation

Preventing sticky cotton is a top concern right now.

 With the popular Big Fresno Fair coming up in a couple weeks, it’s a good bet you will see lots of fairgoers snacking on fluffy, sticky cotton candy. Let’s hope that’s the only kind of sticky cotton we see in the Valley.

Lately, more growers have been treating their cotton fields because of rising aphid populations and an increasing number of bolls opening up. Aphids produce honeydew. When the substance is gets on open bolls, the lint becomes sticky and sticks to ginning and spinning equipment, causing the threads to break. Sometimes the gin won’t even gin the sticky cotton causing a great loss to the grower.

Growers are determining the best time to apply defoliants. 

This means we’re at a crucial time to monitor for aphids and keep them under control. Of course, the first line of defense is natural predators such as parasitic wasps. When the aphid numbers rise to a critical threshold, treatment becomes the final option. Remember to check UC Integrated Pest Management’s online resources for treatment guidelines and materials. The guidelines will help you better discuss aphid management strategy with your pest control advisor.

Looking at the cotton plants, I’m seeing an average of eight to 11 nodes above cracked boll in acala. For pima, I am finding an average of 11 to 13 nodes above cracked boll (NACB).

Growers use the average number of nodes about cracked boll as an aid to determine the right time to apply defoliants, taking into account the potential loss in yield and quality from immature bolls.

Growers apply defoliants to increase the rate of leaf loss and desiccation, which allows for timely and efficient harvesting of cotton. Determining when to defoliate is make on a field-by-field basis. Here’s a link to the UC IPM discussion and online calculator to figure out your NACB. Here’s another site that talks about scheduling defoliation.

Overall, the plants are in good shape and growers could be in store for good yields this season.

Right now, growers are prepping for defoliation in acala. They are using a product to speed up the ripening process to get as much fruit to mature before defoliation. An early planting and the hot August have pushed the season ahead of normal by a week to 10 days. I’m reminding growers to continue monitoring for aphids as well as whiteflies. Pests are still a threat until the plants are defoliated.

Alfalfa nears the end of the season.

Meanwhile, alfalfa yields are starting to drop as the season winds down. We’re pretty much out of the worm season here.

Almonds on the ground are being swept in windrows.

On the almond front, field scout Jenna Horine reports the harvest is in full swing. Growers are shaking nuts off the trees so they can dry on the ground. Some are sweeping up the nuts and while others have sent their almonds to the hullers. Jenna is seeing some debris on the ground in some orchards. That’s a sign that some older trees didn’t handle the tree shaking very well, causing branches and limbs to break off the tree.

 Cotton Tour Reminder: There is still time to sign up for our annual Cotton Farm Tour on Friday, October 19 from 8:30 a.m. to 5 p.m. The tour begins at the Best Western Apricot Inn at Interstate 5 and West Panoche Road, about 23 miles southwest of Firebaugh. It’s a free event filled with plenty of good information. You need to register to reserve a spot in this popular event. Go to the Sustainable Cotton Project website to sign up. Tell a friend.

There Are Always Anxious Times in the Ag Business

“What, Me Worry?”

MAD's Alfred E. Neuman

That’s the popular saying by MAD magazine’s long-time cover boy, Alfred E. Neuman. Could the freckled face lad could be mistaken for a farmer? Indeed, it seems there is always something to worry about in the farm business.

They fret over the weather (it’s too cold or too hot) and over water (there’s too much rain, too little). They worry about commodity prices, expenses, plant diseases and, of course, crop-threatening pests. “What, Me Worry?” Yes farmer do.

Take cotton growers, for example. Just when they stop worrying over lygus, they start holding their breath over aphids and whiteflies. There’s no lack of anxious times in farm country.

Aphids are found on the back of a cotton plant leaf.

Right now the concern centers on aphids in cotton. During my field visits in cotton, I am seeing aphids coming on stronger in some areas, primarily in fields bordered by melons and tomatoes, which are still being harvested. As these fields are drying out and being harvested, the pests are heading for the greener fields of cotton.

 It’s not surprising to see a lot of tomatoes around cotton. Tomatoes are a good rotation crop with cotton. In Fresno County, tomatoes consistently rank as one of the top 3 crops in the area – meaning there are a lot of tomato fields around.

Right now, beneficial insects are helping keep the aphid numbers down. Some growers may be looking at spot treatments. Overall, I suggest growers keep a close eye on aphids and follow the management guidelines by UC Integrated Pest Management.

Greenhouse whiteflies may be migrating from tomatoes.

We’re getting close to the time to defoliate the cotton plants and get ready for the fall harvest. My estimate is some acala are a couple weeks away. The pima varieties, which are harvested later, are three weeks to a month away for defoliation.

Here is a close-up of a Silverleaf whitefly

Turning to whiteflies, I’m spotting them in different areas of the cotton fields.   I’ve heard of one grower treating for the pest in the past week. Other growers are holding off and considering applying insect growth regulators that attack the immatures. I suspect greenhouse whiteflies are coming from nearby tomatoes. It’s unclear where the source of the silverleaf whiteflies. Again, UC IPM is a good reference to managing whiteflies.

In alfalfa, the worm counts are going down. I haven’t heard of any treatments there. Some growers are cleaning up aphids, especially in fields that are next to cotton. We’re about a month away from the end of harvest here.

Spider mites spin a web in a small cluster of almonds.

On the almond front, field scout Jenna Horine says windy, hot and dry conditions are ideal conditions for spider mites to flare up. Some growers are dealing with mite issues. Experts say it’s still OK to treat if the nuts are still on the tree. Here’s a link to the UC IPM pest management guidelines spider mites.

The almond harvest continues with some trees now ready for shaking. Overall, things are going smoothly.

Cotton Tour Approaches: Don’t forget to spread the word about our annual Cotton Farm Tour on Friday, October 19 from 8:30 a.m. to 5 p.m. The tour begins at the Best Western Apricot Inn at Interstate 5 and West Panoche Road, about 23 miles southwest of Firebaugh. It’s a free event packed with lots of good information. You need to register to reserve a spot in this popular event. Go to the Sustainable Cotton Project website to sign up.

Labor Day: Another Day in the Field for Farmers, Pests Alike

 It’s safe to say farmers rarely take a holiday on Labor Day. To them, Labor Day is a busy time of the season and there is little time to relax. You can say the same thing with pests, too.

Indeed, I am seeing cotton growers working daily to manage growing aphid populations in their maturing fields. Because more bolls are opening, growers are treating their fields to prevent a major outbreak down the road. They are worrying about developing sticky cotton down the road.

Thanks to the nagging heat wave that enveloped the Valley last month, I’m spotting more aphids than usual for this time of year. These pests love the heat and they tend to reproduce faster in hot weather. We certainly had our share of heat last month – it was the hottest August in more than a century.

Aphids are on the increase in the Valley cotton fields.
- UC IPM photos by Jack Kelly Clark

Right now, acala planted early in the season (April 15-25) are at 20 to 30 percent boll opening. Pima, which is harvested very late in the season, is at 5 to 10 percent opening.

I’ve heard a few growers have gone all out and using stronger treatments for aphids that essentially wipe out beneficial insects. That can open a Pandora’s Box. By following this route, growers bet the harsher treatment will get through the time to defoliate the plants and eliminate the pest problems.

I call that rolling the dice and betting you don’t get bit with snake eyes. The reason: If there is cooler weather down the road then the boll ripening process will slow down. That means aphids could resurface and force growers to apply another treatment. The defoliation target date is around September 20 with harvest coming around October 15 to 25. It can be particularly tricky with later ripening pima varieties.

For the most part, growers are turning to softer chemicals that will control aphids while protecting beneficial insects. That is the preferred practice for the growers who participate in our project. You preserve biological controls and let natural predators gobble up the aphids. This protects the environment and public health while saving time, labor and money in the long run.

Cotton growers need to monitor their fields for whiteflies.

Another worrisome pest I am spotting in the field is the whitefly. The pest is starting to show up in cotton as nearby tomato fields start to dry. I’m spotting mostly greenhouse whiteflies (here is a picture gallery to distinguish between whiteflies - http://ucanr.org/sites/CottonIPM/Useful_Reources/ with some silverleaf showing up in the plants. Again, the heat has sped up the population buildup and  harvest in other crops is accelerating the migration of whiteflies into lush cotton fields.

To assess whiteflies, you want to examine the fifth leaf down from the terminal. Check the a quarter-sized area between the central and left side main veins and for presence or absence of nympths (3^rd or 4^th instar). Learn more about aphid and whitefly monitoring and management guidelines from UC IPM.

Meanwhile, mites are popping up on some places. They’re most likely coming from nearby almond orchards. These pests can defoliate the leaves and leave you with bare cotton, which increases exposure to pests. For now, mites are a major threat, but they warrant monitoring. Growers also need to keep an eye for worms, which can move into cotton from drying alfalfa and tomato fields nearly.

Some orchards have almonds drying on the ground.

On the almond front, field scout Horine has taken nuts samples from all the orchards and found everything pretty clean. Overall, mites don’t pose a serious problem at the moment. For those growers dealing with mite pressure, they go ahead and spray for the pests if the nuts are still on the trees, says retired University of California entomologist Walt Bentley. In the meantime, hullsplit continues to vary – even within the same orchard.  So far, things are going pretty smoothly.

Save the Date: Spread the word about our annual Cotton Farm Tour on Friday, October 19. Once again, the price is right: Free. We meet at 8:30 a.m. at the Best Western Apricot Inn, 46290 West Panoche Road, Firebaugh. Check the Sustainable Cotton Project website for details and to RSVP.