CROP AND PEST SITUATION

Cotton Insects As I refer to previous issues of this newsletter, we will see that on July 28th (Vol. 27 – No. 11) our average cotton plant, based on the IPM Scouting Program fields, indicated that there were 5.5 nodes above white flower (NAWF). Then the following week, on August 4th the newsletter (Vol. 27 – No. 12) indicated that that week 60% of all fields were <5 NAWF. Therefore, a majority of our cotton reached physiological cut-out (5 NAWF) on or around July 31- August 1. Based on my data as the Levelland National Weather Service Observer for August 1-25 we have accumulated 449 heat units. So, by August 26th a majority of the cotton acres in our scouting program area from Ropesville to Morton and north near Littlefield will have sufficient heat units to meet the criteria of 5 NAWF + 450 DD60 Heat Units to be safe from economic insect damage. The exception to this is cotton aphids. I have not seen cotton aphids in 18 days. So, this is not the “all clear, everyone walk away from the cotton” signal. However, the signal to be very careful in spending money to control an insect situation that will not return in final yield has been given.

Cotton Nematodes Now is an excellent time to soil sample for cotton root-knot nematodes. Soil sampling is important in determining populations of plant parasitic nematodes capable of reducing yield. Nematode samples collected prior to harvest may give the best estimation of nematode populations. In collecting soil samples, several factors, such as sampling method( s), sample preparation and handling and field conditions must be taken into consideration.

Several methods can be used in obtaining soil samples. Samples should be collected following a random, crossing, or zig-zag pattern (Fig. 1). A total of three composite samples (from 1/3 of the field each) should be collected per field. Additional samples may be required if dealing with different soil types in a field. A composite sample consists of 15 to 20 soil cores taken from a depth of 12-inches using a soil probe, or a narrow- bladed shovel. Samples should be taken within a 4-inch radius of the taproot, as it is important to have root fragments present in the sample. The soil cores should be placed in a bucket and thoroughly mixed be- ing sure that any dirt clods are broken-up. A sub-sample of 1-quart should be placed in a sealed plastic storage bag. Nematode samples need to be kept cool (not frozen), and out of direct sunlight. In addition to the collection and handling of samples, field conditions at the time of sampling may impact test results. Close attention should be paid to the amount of soil moisture at sampling. Samples should not be taken if soil moisture is too wet or too dry. Samples should be sent to a qualified laboratory capable of making microscopic evaluations to determine populations. West Plains IPM Update is a publication of the Texas A& M AgriLife Extension Service IPM Program in Hockley, Cochran, and Lamb Counties. Editor: Kerry Siders, Extension Agent-IPM Contact information: 1212 Houston St., Suite 2 Levelland, TX 79336 (806) 894-3150 (office), 638-5635 (mobile), or 897-3104 (Fax) ksiders@tamu.edu (E-mail)