GENERAL SITUATION

Isolated sprinkles fell across the area within the last week. The grain crop really needs a good rain in order to keep filling kernels. Relatively mild conditions as a result of the tropical storm that hit Southeast Texas has provided the Southern Blacklands with a couple of days of mild weather which benefits the grain. On the other hand, the cotton does better when the temperature is above 90 F, and with the early season insect pressure, we need optimum weather for the cotton crop.

More corn continues to tassel and a lot of grain sorghum is heading. Much of the cotton is at or beyond matchhead square and many fields are currently being sprayed for overwintered boll weevils.

CORN AND SORGHUM SOIL INSECT PESTS

Sorghum midge are being found in higher numbers, but well below economic thresholds thus far. Counts range from 0 to 15 per 100 heads checked. I would expect to see populations to steadily increase over the next couple of weeks.

Grasshoppers continue to cause more damage across fields. Currently, some growers are having to treat entire fields of corn where the tassels are being eating to the ear and sorghum where damage is occurring to developing kernels.

COTTON

Cotton ranges from cotyledon stage through one week into bloom, with the majority at 1/3 grown square stage. Square set is ranging between 52% to 76% with most around 65%. The majority of the cotton is averaging about 5 squares per plant.

Thrips continue to cause damage on some of the youngest cotton with moderate terminal damage being found.

Aphid levels have leveled off in most fields this past week. Beneficial insects, including lady beetles, scymnus beetles, green lacewing and minute pirate bugs are being found in moderate levels in many of the aphid infested fields. We are also seeing good levels of minute pirate bugs and green lacewings in many fields, which will be a real plus as the worm numbers begin to increase.

Fleahopper levels remain high. The levels have dropped off from what they were the previous few weeks, but numbers are still well above the economic threshold in fields. Insecticides are providing a couple of days more suppression of adults over what the products did just two weeks prior.

Currently, fleahopper counts range from 2 to 42 per 100 plants with the majority of fields ranging from 10 to 22 per 100 plants.

Boll Weevil populations are being found in some fields now. Punctures range from 0-8 per 100 squares checked. This is the first week this season that we have found punctured squares. Trap catches remain low and are expected to maintain a similar trend until closer to harvest as weevils stay in the fields to feed and reproduce (Table 1).

Some suggested insecticides labeled for overwintered boll weevil include BidrinŽ 8 E @ 8 oz/ac, Guthion 2L @ 1pt/ac, Phasar 3E at 1pt/ac, Vydate CLV at 8.5 oz/ac, and Penncap-M 2F @ 1pt/ac. For products such as Guthion that do not control fleahoppers, it may be necessary to tank mix Bidrin, dimethoate, or Orthene to achieve fleahopper suppression.

Cotton bollworm/budworm levels have increased slightly over the last 7 days. Number of eggs range from 0 to 12 per 100 plants and larvae range from 0 to 8 per 100 plants.

Because of later than normal fleahopper sprays that have gone out, beneficial levels are not at what we would like at this point in many fields. Those growers will have to pay more attention to their fields as worm activity increases. Fields of Bt cotton should be well protected from these sub-threshold levels of worms. However, with that said, this low level of worm activity will help draw in additional beneficial insects.

Management and decision making. Fields should be carefully scouted at least once a week and twice weekly during peak periods of egg deposition. Eggs and newly hatched worms are usually found in the plant terminals and indicate possible outbreaks. Natural mortality agents such as weather and predators frequently control these stages before any damage occurs. Once worms are ˝ inch long, natural control factors are much less effective.

Frequently, examination of the upper third (terminal) of the plant (leaves, stems, squares, blooms and bolls) for eggs and small larvae is all that is needed to make sound management decisions. However, moths sometimes deposit eggs on the fruit and stems lower on the plant. This may occur when cotton plants are stressed and making little new growth, or during periods of high temperatures and low humidity. Detection and control of eggs and small worms are more difficult when eggs are deposited throughout the plant. Also, as bollworm/budworm larvae increase in size, they attack fruit lower on the plant. Whole plant inspections are, therefore, necessary to detect larger larvae.

Terminal/Square Inspection Method. Divide the field into four quadrants and examine 25 plant terminals, selected at random from each quadrant, for small larvae and eggs. Also, from each quadrant, examine 25 one-half grown and larger green squares for bollworms and bollworm damage. Squares should be selected at random and flared or yellow squares should not be included in the sample.

Before first bloom, insecticide application may be justified when 15 to 25 percent of the green squares are worm damaged. Once blooms are present, an insecticide application may be justified when 8 to 12 or more small larvae are present per 100 plant terminals and 5 to 15 percent of the squares or bolls are worm damaged. If worm numbers are high, it may not be appropriate to wait until the damage threshold of 5 to 15 percent square damage is reached.

If previous insecticide applications have eliminated natural enemies, fewer bollworms/budworms can be tolerated before economic damage occurs. If insecticides have been applied after first bloom and have eliminated natural enemies, treatment may be justified when infestations reach or exceed 4 to 5 small worms plus eggs per 100 terminals and 5 percent of the squares and small bolls have been damaged by worms.

Microbial insecticides may be considered during the squaring period through the first 10 days of blooming if infestations average 12 or fewer small (less than 1/4 inch) bollworms per 100 terminals. Unlike conventional insecticides, microbial insecticides do not destroy predators and parasites.