Lygus have been fewer this week. Stinkbugs can be found but nothing alarming. Cotton aphids are being found occasionally. Bollworm eggs are not resulting in worms. Beet armyworms are not common this week, old damage can be seen. Beneficials such as spiders, big eyed bugs, assasin bugs, lacewing, and lady beetles can all be found in fairly good numbers, especially crab spiders. Square set has generally been better than 70%. A few fields with low square sets have been explained by fleahoppers, and possibly Lygus. However, a few fields with low square set (50-60%) can not be blamed on insects or easily explained by some other particular factor or event. I suspect that it is a physiological response to some environmental stress. Also, some fields which I have seen this occur have been fields with high plant populations +80,000, this includes some ultra narrow row with +110,000 plants per acre. Shading and plant to plant competition will be the blame in these situations.

Cotton 101 - The Squares
Under normal conditions, you can expect to see the first square between five and eight weeks after cotton is planted. Keep on the High Plains, the first square normally appears between 43 and 47 days. Watch for white blooms about three weeks later. The first square is formed on the lowest reproductive branch of the plant. This branch may be located at the fifth to the ninth main stem node. If you don't have squares by the ninth node (as an average of the fields), your crop may be in serious trouble. The critical period for producing squares is from June through mid July. The squaring rate should increase 1 ½-fold to 2 ½ fold or more each week through the fourth week of squaring. This rate usually levels off during the fifth and sixth weeks, then drops sharply at any time up through the fifth week.

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 1000F 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 periods 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.

Educational programs conducted by the Texas Agricultural Extension Service serve people of all ages regardless of socioeconomic level, race, color, sex, religion, handicap or national origin. The information given herein is for educational purposes only. References to commercial products or trade names is made with the understanding that no discrimination is intended and no endorsement by the Cooperative Extension Service is implied.