Tranquility, Calif. grower Keith Eubanks says this is the year he and fellow cotton farmers can no longer bewail themselves as producers of “poverty weed.”
Cotton prices have transformed the lint crop’s dishonorable coffee shop moniker into one that has growers wondering what they can do to coax a few more bolls from their plants in order to capture more cash from the highest cotton prices ever.
Tantalizing in that discussion is the fact that a cotton plant has potential to produce twice as much fiber as it normally does — but doesn’t for a number of reasons, mostly physiological.
Still, growers are wondering if they need to change lygus bug pest control threshold levels to protect $2 cotton differently than 75 cent cotton.
“You can’t spray a three-and-a-half bale cotton crop into a four bale crop,” says University of California IPM Specialist Pete Goodell.
Peter Ellsworth, University of Arizona IPM coordinator and director of the Arizona Pest Management Center, agrees.
However, Ellsworth, who has done cost-benefit economic research on cotton, says fiber prices are now so high that there could be an economic benefit from protecting desert cotton later in the season than normal.
That scenario depends on many factors, he says.
Both Ellsworth and Goodell agree there is absolutely no economic justification for modifying the basic Integrated Pest Management threshold treatment recommendations for lygus just because cotton prices are the highest in 150 years.
“I have already had phone calls from growers and PCAs asking if they should change threshold levels due to the high price of cotton,” Ellsworth says. “These are the kinds of questions growers and PCAs should be asking, even though lygus questions do not normally come up until July.”
Neither he nor anyone expected cotton prices to reach the current stratospheric levels. But, several years ago he did an in-field economic analysis on the question and found that there is no need to change the basic Arizona 15 total lygus/4 nymphs lygus treatment threshold level.
(See related article in this e-newsletter explaining the 15/4 threshold recommendation.)
“There was no incremental change in yields for additional lygus control below the 15/4 threshold in raw data or model data,” Ellsworth says. “We sprayed quite often below the 15/4 threshold level and recorded no additional yield.”
However, that is only half of the economic discussion about protecting high priced cotton against lygus damage in a year like 2011.
“The second question is, when is the last effective economic spray advisable for lygus control?” says Ellsworth. “Where is the economic tradeoff point for curtailing or stopping lygus control based on the 15/4 threshold level?”
Up to $1 per pound it doesn’t change — but it does at about $1.25 per pound, he determined from his research (http://ag.arizona.edu/crops/presentations/DRAFT_LT_guide2-pg.pdf). “This is when you start to see the additional benefit of extending lygus control later in the season than would normally be economically justified,” he says.
The change might be subtle, noted Ellsworth. “We’re not talking about an extra month of control here, perhaps at most one to twoweeks ‘extra’time to make that last effective/economic spray,” he said.
“Specifically, if after reviewing UA’sLygus termination guidelines, a grower determinesthat the last spray should be made no later than NAWF=5 (for say 75 cent cotton), you might see that timing shift to about NAWF = 3 or 4, which could occur quickly (1 week) or take a bit longer (2 weeks) depending on how quickly the crop is progressing through cut-out,” Ellsworth explained.
But, it is not as simple as that extra 25 cents. It depends on whether the variety is early, medium or late maturing; when it was planted; the stage of flowering in the field; a grower’s production plan; irrigation timing; whether to go for a top crop; and the harvest target date.
Arizona, Australia and the Middle East are among the few places in the world where a late season lygus treatment may make sense. In most other areas, like the San Joaquin Valley, the potential for wet fall harvest weather virtually precludes a grower facing such late season decision.
Ellsworth cautions that even in the desert, the window isn’t open forever. “We’re still waiting for green bolls from last Christmas to open — and it is May,” he laughs.
Arizona growers are “generally conservative and less susceptible to changing their historical production plans,” he says
Although he hasn’t swept any cotton fields for lygus, he doesn’t expect a challenging year from the state’s No.1 cotton pest.
“Lygus in alfalfa looks pretty typical for this time of year, and there has been no winter moisture to produce a lot of broadleaf weeds to harbor the pest,” he says.
The crop is about a week behind normal — not as far behind as is in California, which had a wet cool spring and so far a cooler than normal early summer.
However, Ellsworth sees a potential lygus problem in the middle of cotton fields.
“Growers were so excited about cotton that they didn’t thoroughly take out some of the alfalfa stands, and I’ve seen cotton fields that have significant patches of alfalfa in them. What they have is a great lygus host in the middle of their cotton fields.
“I’ve seen this situation before, but never to the degree as this year. I’m hoping growers will get it under control soon enough, so there will be no harm/no foul.”
In California’s San Joaquin Valley
It has been far cooler in the San Joaquin Valley where Pete Goodell estimates the crop is two to three weeks late — which will challenge growers to set and hold the bottom crop.
But, he says, the rules are the same for lygus treatment thresholds this year as any year, regardless of whether the fiber is worth 70 cents or $2 per pound.
(See related story in this e-newsletter for monitoring and treatment recommendations developed by University of California entomologists)
“I don’t expect to see a lot of blooms by the normal July 4 date,” Goodell says. “The crop is two to three weeks later than normal.” But, fields don’t look stressed, he notes.
“It has been cool, but not cold and wet. Plants really look good, but they are growing out slowly. There is no question we really need to watch the first boll set because I still expect lygus to be moderate to severe this year.”
One reason, he says, is that safflower, a major sink for lygus, has not flowered and that may coincide with cotton’s early season susceptibility to lygus damage on squares. Weeds also are still plentiful in the cool weather. (See 2011 Lygus Survey at http://cottoninfo.ucdavis.edu/IMAGES/FieldCheck_May_27_2011.pdf)
“The best thing growers and PCAs can put in their fields this year is their shadows, and be ready to make the call when it is needed.”
There is no question, he says, that this will be a challenging year for SJV cotton producers, with good prices underpinning each management decision.
“We have some good products available to use when thresholds are reached, so we can manage lygus early without blowing everything up” and spawning secondary pests.
Goodell doesn’t believe it is so late that squaring will begin at the eighth node as one would expect from a wet, cold early season. Rather than first squaring at the fifth or sixth node, he expects squaring to be delayed to perhaps the sixth or seventh node.
He echoes Ellsworth’s sentiment that treating sub-threshold levels of lygus will only be spending money without making any additional yield.
Lygus control decisions must also be made on plant-based measurements, Goodell says.
“Know what the plant is supposed to hold for the time of the season. Monitor square retention while sampling the lygus population. If in doubt, split squares and look for earliest feeding damage form lygus. Make very good, solid decisions based on yield potential.
“If you have an 8 count of lygus but the plants are holding 80 percent of top squares, there is not a problem. If you have a lygus 5 count and you are holding only 50 per cent of the squares when you should be holding 70, lygus may be a problem.”