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Vol. 18, No. 2, May 31, 2000 |
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Vol. 18, No. 2, May 31, 2000 |
| Cotton Situation: Cotton
is growing well in response to a warm May. You wouldn't think it
had been such a warm May based upon the high temperature on May 30.
It may have gotten up to about 70°, following an overnight low in the
upper 50's. Last night we had another cool evening with temperatures
generally in the low 50's. Most cotton plants are currently in the
2-4 leaf stage. Although there is still cotton in the cotyledonary stage,
and fields left to plant, there are a few cotton plants out there with
squares, believe it or not.
Cotton Insect Hotline: The South Carolina Cotton Board is sponsoring a Cotton Insect Hotline (1-877-629-1474) this year, that will be used to transmit timely information about cotton pests and cotton production. The Hotline will be updated on Tuesdays and Fridays. Since it is primarily about insects, most of the messages will deal with these issues. But the May 26 message was recorded by Dr. Mike Jones, and he discussed several agronomic topics. We will hear from him from time to time during the course of the cotton-growing season, and we may even be able to coax Dr. Ed Murdock to record some advice relative to weed management. South Carolina Cotton Board: While I'm on the subject of the South Carolina Cotton Board, I understand there is a referendum going out to cotton farmers allowing them to vote on whether or not to continue the cotton marketing order. As you know, funding is provided through the Cotton Board for cotton research in South Carolina as well as marketing. Those of us who work in cotton for Clemson University have received funding to investigate many aspects of cotton production and pest management. When special problems have surfaced that have been unique to our state, these funds have been of tremendous assistance in our investigations of the problems and in our attempts to devise management solutions. One of the best examples that I can think of involves pyrethroid resistance in bollworms. After the problem was diagnosed in 1996, the Cotton Board provided startup funds the very next year to allow us to trap bollworm moths and run vial tests for resistance both above and below the lakes. Funding has continued through the present growing season. We have also tried to stay on top of the development of resistance through collections of worms in fields where pyrethroids have not provided satisfactory control. As we have learned more about the resistance situation, we have been able to develop a management plan that should allow us to slow down the resistance merry-go-round, and keep pyrethroid in our arsenals for a longer time. I should also mention that the Clemson University Cotton Team brings other funds to the table that are directed toward these research and extension efforts. Every dollar provided by the Cotton Board has attracted several dollars from other funding sources, which contributed to salaries, travel, equipment, supplies, etc. Finally, I just want to say that we (M. Roof taking the liberty of speaking for the cotton team) have always greatly appreciated your commitment to our programs, because you are why we are here. Cotton Insect Situation: Well I finally got around to the cotton insect situation. As I said on the Cotton Insect Hotline yesterday, thrips are about the only thing happening right now in the way of insect pests in cotton. I was looking at some of Dr. Phil Bauer’s ultra-narrow row cotton on Monday and was a little surprised to see lots of thrips on cotton that had just come up to a stand. Small grains are past the stage where western flower thrips or tobacco thrips (two of our major species) should be emerging from their heads, so that would leave wild host plants as the primary source of new infestations. Within the next few days I expect to see a decline in thrips pressure, but if you have cotton just coming up you should be keeping a cautious eye on these plants in the event that a foliar application of Orthene, dimethoate, Bidrin, or Monitor is needed. I haven't been satisfied with the levels of thrips control with foliar sprays that I have seen to this point. Thrips seemed to be hanging on longer than expected and they have been doing more damage to the plants than expected given the warm temperatures. The slow growth from lack of moisture may have contributed to this problem with foliar treatments, as it has diminished efficacies of soil applied insecticides as well. Still, a few crinkled leaves will probably not create a problem with delayed maturity. Maturity delays usually stem from the destruction, or serious injury, of the terminal buds. Post directed herbicides are another matter entirely, and delays in applying post directed treatments in conventional cotton could result in weeds getting an unfair advantage in the growth race. In Roundup Ready cotton the problem of thrips-stunted seedlings would appear to be much less of a problem, since Roundup may be applied over the top. Yellow-striped armyworms
are a colorful addition to a few plants in many cotton fields. Sometimes
they seem to like the pigweed better than cotton, but to my knowledge there
have been no serious problems with these insects. These are the black
velvety looking worms with yellow strips on each side. You will find
them just feeding on leaves, not cutting plant stems. If you are
seeing plants that have been cut off you may want to dig around and look
for cutworms in the soil. Cutworms can be difficult to find,
but if you have the patience, and desire, you can slowly scrape away the
soil in the vicinities of cut plants until you expose them. We saw
grasshoppers simulating cutworm damage last week in a minimum tillage
situation. As the cotton seedlings would pop out of the ground the
grasshoppers would chop off their heads and eat the tops. A 20-acre
field had to be replanted and a pyrethroid was applied to control the grasshoppers.
Mitchell Roof
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| This information is supplied with the understanding
that no discrimination is intended and no endorsement by the Clemson University
Cooperative Extension Service is implied. Brand names of pesticides are
given as a convenience and are neither an endorsement nor guarantee of
the product nor a suggestion that similar products are not effective. Use
pesticides only according to the directions on the label. Follow all directions,
precautions and restrictions that are listed.
The Clemson University Cooperative Extension Service offers its programs to people of all ages, regardless of race, color, sex, religion, national origin, disability, political beliefs, sexual orientation, marital or family status and is an equal opportunity employer. Clemson University Cooperating with U.S. Department of Agriculture and South Carolina Counties. Issued in Furtherance of Cooperative Extension Work in Agriculture and Home Economics, Acts of May 8 and June 30, 1914. Public Service Activities |