West Plains
IPM Update


news about integrated pest management in hockley and cochran counties
Kerry Siders, EA-IPM
(806) 894-2406 (phone)
(806) 638-5635(mobile)
(806) 897-3104 (FAX)
E-Mail: k-siders@tamu.edu   http://lubbock.tamu.edu/ipm  
Vol. 7, No. 8
1212 Houston Street, Suite 2, Levelland, TX 79336
July 8, 2002

IN THIS ISSUE:

* Crop and Insect Situation
* Heat Units
* Cotton 101 - The Blooms

CROP & INSECT SITUATION
Most everyone has now received a rain. Even western Cochran County received up to two inches in places. We are in dire need of sunshine and consistent heat to take advantage of this good moisture. Many cotton fields are growing well vegetatively, yet we need to shift some of this growth energy to reproductive regions. We have quit a lot of horse power behind fields which are now at bloom stage. In most fields which are blooming we have an average of 9.5 nodes above white flower. One concern is that we have the top 4 nodes really stretching out, some in excess of 2 inches. This is a sign that vegetative growth is a dominate sink and not the reproductive growth. Yet, square retention is exceptional right now. On average in the scouting program fields we are at +90% square retention. If we can maintain this level for awhile those squares and resulting bolls will definitely become a major sink for energy and slow the vegetative growth.

Insect pests remain quiet. Scouts are finding cotton bollworm eggs and larvae at less than 2500 per acre in one out of ten fields. Cotton aphids have been found in one out of ten fields.

These aphids have been confined to the terminal region. I am not overly concerned about this since we still have a good beneficial base. Crab spiders, lady beetles and a developing lacewing population will utilize these low number of pests to sustain themselves. Fleahoppers and Lygus can be found, but are more prevalent on other hosts. I am hoping that we can slip by any major fleahopper problems. I am however, concerned about Lygus as we move further into the season.

HEAT UNITS (DD 60's)

May 1st to Present ...................................938
May 11th to Present .................................843
May 21st to Present .................................784
June 1st to Present ..................................648

GROWTH STAGE HEAT UNITS
Planting 0
Emergence 75
First Square 450
First Bloom 900
First Mature Boll 1800
First Open Boll 1900
5% Mature Bolls 1975
95% Mature Bolls 2270

 
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Cotton 101 - The Blooms
The cotton plant develops in an orderly, predictable pattern. If you are familiar with the fruiting stages, their sequence, and the time required for each stage, you can tell if your crop is on schedule. For example , you should spot the first white bloom 60-80 days from planting. That will be from 20 to 27 days (23 days average) after the square or bud develops. It will take about 3 days between the opening of a flower on one fruiting branch and the opening of the bloom in the same position of the bloom in the same position on the next higher fruiting branch. That's known as vertical flowering. About 6 days pass between the appearance of two consecutive blooms on the same branch (horizontal flowering). The cotton bloom is a perfect flower. It has both male parts (pollen-producing stamens, each with a double -lobed anther) and female parts (stigma, style, and ovary) in the same flower. The ovary has 4 to 5 carpels or locks. Each lock contains 8 to 12 ovules that may develop into seed. Flowers open during the morning, and pollination usually occurs within a few hours. Pollen grains from the anther drop to the sticky surface of the stigma.

Fertilization - the union of a male reproductive cell from a single pollen grain and a female cell in the ovule - normally takes place within 24 to 30 hours after pollination. The fertilized ovule develops into a seed. Some of the ovules may not develop fully or are aborted. If a majority of the seed abort, the boll will fall off the plant within 7 to 10 days after flowering. Cotton flowers usually are self - pollinated. However, bees or other insects may increase the frequency of cross-pollination. Temperatures above 100 degrees F and moisture - rain or high humidity - reduce pollination. A bloom will not pollinate after the first day. The white petals of the flower turn pink after 24 hours and shed within a week as the fertilized ovules of the ovary grow into a boll. The effective bloom period occurs from early July to mid-August. Stress during this period will cause the largest loss of yields.

Research shows that in the High Plains, about 85% of the total bolls are set during the first three weeks of blooming,10%during the fourth week, and less than 5% from the fifth through the seventh weeks.

West Plains IPM Update is a publication of the Texas Agricultural Extension Service IPM Program in Hockley and Cochran Counties.

Editor: Kerry Siders
Production: Patty Castaneda


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