Monday, June 25, 2012

Let's Draw a Roadmap for a Successful 2012 Cotton Crop

Remember drawing a treasure map as a kid. You drew elaborate lines and plotted landmarks leading the treasure awaiting the end of the hunt.

I relived those days many times in the past week. In this case, the treasure is a sea of fluffy white cotton fiber awaiting growers during the fall harvest. I spent hours mapping the fast-growing cotton plants across the Valley.

- Graphic by Texas AgriLife Extension Service 
Plant mapping can be rather simple. You don’t need to be a Van Gogh or make it complicated.  In fact, by making it easy, you are likely to continue mapping the development of your cotton plants. The work will help you make future management decisions and give you a good indication of the yield in the fall.

I’m seeing plants with 80 to 100 percent fruit retention – a very good rate. For Acala upland cotton,  growers normally can expect a 60 to 70 percent retention rate. Pima cotton is a little less precise to predict.

Lygus, however, is in full force in the cotton fields. It’s not surprising to see numbers rise following the third cutting of alfalfa in nearby fields. On the positive side, the lygus population could be even higher in cotton if growers didn’t follow best management practices and leave strips of uncut alfalfa to keep the pest from migrating into cotton.

Growers need to keep an eye on lygus in the coming weeks.
Still, cotton growers need to continue monitoring their fields and follow the trends carefully.  You can download a pdf of UC Integrated Pest Management’s guidelines about fruit retention and lygus monitoring.  It includes a handy chart to record your monitoring information.

I want to caution growers about jumping the gun on pest treatments. For example, I checked a field last Monday and found eight to nine adult lygus in my sweep net, which would put you at the threshold of treating your field. But a few days later, I re-checked the field and found the numbers had dropped to three to four lygus per 50 sweeps of my net.  The likely reason for the drop is the lygus “took a drink” in the cotton field and then returned to the nearby alfalfa field. Lygus actually prefer the conditions found in alfalfa.

So far, I haven’t heard or seen growers treating their cotton fields for spider mites and lygus. That’s good. Usually you will see growers on their first or second treatment this time of year. My guess is the strip alfalfa and the increase in hay acreage is dampening the pest pressure in cotton this year.

We’ve finished collecting petiole, or leaf stem, samples and sent them off to the lab. The results should be back in about a week. That will give us an idea whether plants need more nitrogen or have been fertilized too much.

Before the season heads into July, I want a take a look back at the spring. With the recent heat wave, plants are developing ahead of schedule. I wouldn’t be surprised to see cotton planted early in the season to starting blooming by the end of this week. Normally, you see bloom around the Fourth of July. An early bloom extends the growing season. It also gives growers a little insurance against early fall rains.

Beet armyworms are on the rise in Valley alfalfa fields.
- UC IPM photo
Looking at alfalfa, I’m finding a slight increase in beet armyworms. It’s important for alfalfa growers to conduct weekly pest monitoring and scout their fields before cutting. That way, you can determine if treatment is needed to prevent pests from migrating to nearby fields such as tomatoes and cotton. The good news is I haven’t heard of any growers treating for worms. Good management practices do pay off.

Monday, June 18, 2012

Cotton Growers Think It's a Cool Time for a Heat Wave

I hope you wore plenty of sun protection because of the furnace-like weather we are having, especially over the weekend.  With temperatures hitting triple digits – surging to a record-setting 109  degrees Sunday, breaking the previous high of 107 in 1917  – it must mean one thing: Summer is around the corner – officially Wednesday. But who’s counting with this heat wave. )))  

For our cotton growers, the sizzling triple-digit weather means ideal conditions for faster development of the plants. It also means growers need to remain vigilant about monitoring for pests. So far, I’m finding fields with light lygus counts. On average, I’m collecting about one lygus nymph and no adults during 50 passes of my sweep net. That’s good.

In the meantime, spider mites appear to be under control, thanks in part to the large number of thrips feeding on mite eggs.

With growers finishing up their first irrigation, it is now important to start plant mapping. This will help you track the development of the cotton plants. At the moment, plants are at their 10th and 11th nodes.
This is the time to check for the percentage of fruit retention. Count the top five and bottom five fruiting branches. This lets you know how the plant is doing. As a rule, an 80 percent or higher square retention is ideal going into bloom. UC offers a dandy online calculator to determine the percentage of retention.
If retention drops, growers might opt to use growth regulators to enhance development. But don’t get too excited about getting an early jump on treatment. Check with you pest control advisor, local UC farm advisor or even myself. I’m happy to answer your questions.

Another task for growers is taking the first petiole analysis of the season. You should take the petiole on the third node on the top of the plant. I suggest taking samples from about 40 different locations in the field and then send them to a lab for analysis. The results will show the nitrogen levels in the plant and indicate whether you are using too much or too little fertilizer. The analysis is worth the investment.

At the moment, I haven’t heard about growers treating their fields for mites, aphids or lygus. That’s a good sign. Usually, this is a time for these pests to start building up. If you are going ahead with treatment, make sure you pick softer materials without organophosphate (OPs).

Alfalfa growers are on their third cutting. Some are starting their harvest while others are already baling their hay. Four or five more cuttings are left this season.

I’m seeing lygus counts on the rise in alfalfa. In the past week, the amount of lygus has increased by about 50 percent. We don’t want them reproducing and migrating into nearby cotton fields. It’s really important now for growers to leave more strips of uncut alfalfa. If you have your own sprayer, you might want to consider treating the strips for lygus. Of course, use softer materials that protect the environment and beneficial insects.
A strip of uncut alfalfa is a good BMP to keep lygus from moving to cotton.
The best IPM practice in alfalfa is to leave a strip creating a home for lygus and to keep them from heading into a cotton field. Here’s my suggestion for determining how alfalfa to leave uncut: 1 swath for every 30 to 40 acres of hay grown in the field.
We had a good turnout for last week’s Cotton Field Day. I want to thank Dr. Pete Goodell of UC IPM and UCCE Fresno’s Dan Munk for their presentations. If you missed their talks or want a refresher, the Sustainable Cotton Project has posted them on our website: or on YouTube – for Dan’s presentation and Pete’s discussion. There is plenty of useful information. Check them out.

Monday, June 11, 2012

X Marks the Spot for Sweeping Your Fields to Monitor Pests

Cotton growers are finishing the first crop irrigation.

Cotton season is in full swing with growers now wrapping up the first irrigation. The watering, mixed in with fertilizer folded into the soil earlier, are now combining to help these plants thrive and develop lots of fruit.

I’m spotting the first pinhead squares at the fifth to sixth node. That’s a good sign because normally you find the first pinheads developing at the sixth to seventh nodes. This means the plants could develop more fiber-bearing fruit, likely translating into a higher yield at harvest time.

At this plant development stage, growers now need to be more vigilant about monitoring for pests, especially lygus, the bane of all cotton growers. Lygus can damage squares at all stages of development. It’s important to monitor for this pest to keep the first crop.
Lygus can be trouble.
- UC IPM photo

In this high-tech age, the most effective way to monitor for lygus is the old-fashion way – using a sweep net.
 Here’s the field scout’s short course on sweep net sampling: Pick three or four different locations of the cotton field to perform the sweeps. Picture a big “X” overlaid on top of your field and take your pest samples at each leg of the X. This ensures your locations are equally spaces out to give you a good overview or sample from your entire acreage. You also can follow a “V” pattern. 

 Net sampling should be done weekly. Also be sure to rotate the sample locations to ensure you cover all areas of the field.

The technique is pretty straight forward. As you walk down a row, you move in a sweeping motion back and forth or right to left (left to right if you’re a lefty). Image the sweep net as a tennis racket. One sweep is a forehand move and the second sweep is a backhand motion – Spanish tennis superstar Rafael Nadal would be proud. In each location, you want to do 50 sweeps.

Check the UC IPM online for lygus monitoring for cotton for more information about sweep net sampling and pesticide treatment thresholds. I can’t stress it enough, now this is the time to be vigilant about regular pest monitoring in the field. Spending time and labor on this task, saves time and money in the long run by reducing chemical inputs and costs as well as increasing yields.

It's important to monitor
for pests with a sweep net.
- UC IPM photo
This also is the time to do plant mapping. While I tell growers a plant can hold only so much fruit, the idea is to achieve the ideal maximum amount of fruit. Mapping isn’t an exercise in cartography – the art of making maps. The real world application is simple: Mapping lets you track the plant’s growth and development throughout the season and plays an important role in treatment and management decisions. Again, here’s a UC link to learn more about cotton plant mapping.

Right now, some growers may want to use growth regulators to slow vegetative growth and set more fruit. However, I suggest growers not jump the gun on this. With the first irrigation taking place and fertilizer already feeding the plants, cotton plants are getting food to grow. Applying growth regulators at this same time would seem counterproductive.

This also is a good time to take plant tissue samples. By analyzing the tissue, you can get a read on the level of nitrogen, or fertilizer, in the plant and decide if the plant is getting too much nutrients or not enough. I’ll speak more on this topic in my next blog.

Fusarium wilt is more evident in fields.
On the plant disease front, I am seeing quite a bit of evidence of fusarium wilt damage. It’s the most I’ve seen in the past couple of years. Weather may be a factor causing this problem. I would check in with Fresno County’s UC Cooperative Extension cotton specialist Dan Munk about any concerns in your field.

Looking at alfalfa, growers are finished with the second cutting and now moving onto irrigating again and applying nitrogen to feed their crop. I’m spotting a light amount of worms and an uptick in lygus.

So far, growers are doing a good job of leaving uncut strips of alfalfa to prevent lygus from migrating to nearby cotton fields. It hasn’t reached the point yet where growers need to treat their alfalfa. Natural predators seem to be keeping crop-damaging pests in check at the moment. Again pest monitoring remains important here as well.

Cotton Field Day: Remember Tuesday’s event (June 12) will be from 10 a.m. to noon at the Housley and Vandenberg Farm on Sierra Avenue in Firebaugh. We will feature UC IPM advisor Dr. Pete Goodell and farm advisor Dan Munk. They will offer valuable tips for early season pest and agronomic management.  Directions are available in the events section of the Sustainable Cotton Project’s website –  One and a half hours of continuing education credits have been approved. It will be worth your time to get your questions answered directly from these UC experts. I will see you there.

Monday, June 4, 2012

Cotton Plants Getting Ready for the First Irrigation of Season

As we say hello to June and good-by to May, we can certainly look back at a month of near record temperatures – both on the minimum and maximum sides. These yo-yo temperatures played roles in early season decisions for growers of all crops.

First, let me put my weather hat on and review the historical climatological data for the Fresno region from the National Weather Service. Normally, our temperatures average in the 80s (see chart below), steadily rising as we head toward Memorial Day.

As you can see in the temperature chart I put together, May 2012 (the top darker green line) certainly had its ups and downs, including the last week of the month. On May 9, the thermometer officially hit 98 degrees (probably in the 100s in some hot spots), coming close to all-time record high of 101 on that date, which was recorded in 2001.

Then on May 25, Mother Nature caught a cold and sent temperatures plummeting to reach a high of only 69 degrees, close to the all-time minimum high temperature of 68 reached back in 1890. The weather slowly warmed up in the past week, hitting a torching 104 last Friday – the first day of June.

For cotton growers, who have finished applying fertilizer to their crop, it might be wise to put off their first irrigation of the season until at least Tuesday. Because of crazy temperature swings, the number of heat units hasn’t reached a high enough threshold to make it ideal to start irrigating the cotton.

The timing of the first irrigation could make the difference of a yield increase of 400 pounds of cotton lint per acre, according to University of California researchers. (UCCE pdf) Air temperature changes, drying winds, rainfall since pre-irrigation before planting and rooting volume due to diseases and soil conditions are factors in scheduling the first irrigation.

Here's an example of a pinhead square.
You want to make the young cotton plants a little thirsty and cause a little stress, pushing the pinhead squares to develop on sixth or seventh node. This way, you will get more fruiting branches. If growers irrigate too early, that can stimulate vegetative growth in the plant. Then they might have to spend money on plant growth regulators. For now, I’m seeing growers preparing ditches and laying out pipes, but not yet starting the water.

On the insect front, some fields are experiencing light damage from thrips. But I expect plants to recover from any damage, so there’s a good chance growers won’t have to treat for this pest. On the plus side, the thrips are feeding on the spider mite eggs, which should keep the mite population down. I’m spotting a few more mites in some fields. I suspect that’s due to the relatively dry winter we experienced in the Valley.

Meanwhile, the early review on the alfalfa crop is the yields are looking good. There haven’t been any major pest threats so far. Still I suggest growers keep monitoring for worms.

Save the Date: Remember to put June 12 on your calendar for our Cotton Field Day. We will feature UC IPM advisor Dr. Pete Goodell and UCCE Fresno County cotton specialist Dan Munk. They will offer valuable tips for early season pest and agronomic management during the 10 a.m. to noon event at the Housley and Vandenberg Farm on Sierra Avenue in Firebaugh. Directions are available in the events section of the Sustainable Cotton Project’s website –  One and a half hours of continuing education credits have been approved. Bring your questions.