IN THIS ISSUE

· TPMA Website
· Upper Coast IPM Program Sponsors
· Cotton Insect Situation
· Wharton County Cotton Aphid Test
· Boll Weevil Trap Counts
· Sorghum Midge Watch
· Sorghum Head-Feeding Bugs
· Did You Know

TPMA Website

The Upper Coast Crop Improvement newsletter and other Extension IPM Program newsletters from across the state can be viewed at the Texas Pest Management Association website at www.tpma.org.

Upper Coast IPM Program Sponsors

Cotton Insect Situation

Growth stages of cotton in the Tri-County area of Wharton, Jackson and Matagorda Counties range from matchhead square through the first week of bloom.

Aphid numbers decreased significantly during the past week. Ninety seven percent of the fields monitored were considered light in aphid numbers. Tremendous numbers of parasitic wasps were found during the past seven to ten days. Evidence of their presence can be found by the high numbers of aphid mummies on the undersides of the cotton leaves.

Fleahopper counts were below economic threshold levels in all the fields that were monitored during the past week. Boll weevil punctured square counts ranged from 0 to 2% during the past week. During the past week, boll worm eggs were found in 80% of the fields. Boll worm egg counts in fields ranged from 0-12% throughout the week. Boll worms were found in 53% of the fields. Boll worm numbers in fields ranged from 0-7% during the week. Boll worm damaged squares were found in 10% of the fields. Square damage ranged from 0 to 2% during the week. Brown stink bugs were found in low numbers in 17% of the fields during the past week. Other pests that were found in low numbers during the past week included loopers, saltmarsh caterpillars, and grasshoppers.

Wharton County Cotton Aphid Test

A test was conducted to evaluate the efficacy of selected insecticides against cotton aphids in early blooming cotton. Plots consisted of 4 rows (39-inch centers) x 30 feet. Treatments were arranged in a randomized complete block design and replicated four times. Insecticides were applied on 24 of May with a CO2 backpack sprayer and a two row hand held spray boom with two nozzles per row. Sprayer was calibrated to deliver 10 gpa through teejet hollowcone tx4 nozzles at 45 psi. Ground speed was 2 mph. Treatment efficacy was evaluated by sampling 5 tagged plant terminals (all apical shoot growth above and including the first fully expanded leaf) from each plot. Treatments were evaluated on 3 and 6 days after treatment. Data were analyzed with ANOVA and means were separated according to the LSD test.

Extremely high numbers of parasitic wasps and other beneficial insects were present when insecticides were applied. This is quite evident when observing the numbers of live aphids and aphid mummies in the untreated check 6 days after treatment. Also, 1.25 inches of rain was received 5 days after treatment.

Table 1. Efficacy Of Selected Insecticides Against Cotton Aphids, Michael and Lonnie Beard, 2002.

Means in a column followed by the same letter are not significantly different by ANOVA (P=0.05; LSD).
^a All apical shoot growth above and including the first fully expanded leaf.
^b Days after treatment
^c A non-ionic surfactant at 1 oz/acre was added.
^d The P>F is based on transformed, [square root (x + .5)] , data values; it is inappropriate to list DMRT values based on transformed data.

Boll Weevil Trap Counts

The boll weevil trap line is located in Wharton County on farm to market highway 1162, county roads 442, 422, 409, and 426 and farm to market highway 441 between El Campo and Hillje.

Table one compares trap counts for the months of March, April and May of 2002 to the three prior years and table two compares the Wharton County trap counts to the trap counts in San Patricio and Nueces Counties for 2002. The San Patricio and Nueces County trap line is in an active boll weevil eradication zone.

Table 1. Number of boll weevils captured per pheromone trap per month, thirty-two mile trap line. Wharton County, Texas. Texas Cooperative Extension operated traps.

Table 2. Boll weevils/pheromone trap per month, Texas Cooperative Extension operated traps.

* Currently in an active boll weevil eradication program. Program was initiated by conducting a diapause program in 1996 and 1997. Season long program was implemented in 1998, 1999, 2000, 2001 and currently into 2002. San Pat and Nueces traps run by Dr. Roy Parker, Extension Entomologist at Corpus Christi, Texas.

Sorghum Midge Watch

A significant number of sorghum acres will not have completed flowering as the month of May comes to an end. Generally, sorghum fields in the Upper Coast area need to be through flowering by the first 3 or 4 days of June. Another reason sorghum midge could be a problem this year is due to our extended range of planting dates this year. Especially in fields that will reach the bloom stage 3 or more weeks after older sorghum began to bloom. Sorghum midge numbers increase rapidly because of multiple generations during a season and when sorghum flowering times are extended by a range of planting dates or sorghum maturities. Early-season infestations in sorghum are usually below damaging levels. As the season progresses, sorghum midge abundance increases, especially when flowering sorghum is available in the area.

Because sorghum midges lay eggs in flowering sorghum grain heads (yellow anthers exposed on individual spikelets), they can cause damage until the entire grain head or field of sorghum has flowered. The period of susceptibility to sorghum midge may last 7 to 9 days (individual grain head) to 1 to 2 weeks (individual field), depending on uniformity of flowering

To determine if adult sorghum midges are in a sorghum field, check at mid-morning when the temperature warms to approximately 85o F. Sorghum midge adults are most abundant then on flowering sorghum grain heads. Because adult sorghum midges live less than 1 day, each day a new brood of adults emerges. This fact requires sampling almost daily during the time sorghum grain heads are flowering. Sorghum midge adults can be seen crawling on or flying about flowering sorghum grain heads.

The simplest and most effective way to detect and count sorghum midges is to inspect carefully and at close range all sides of randomly selected flowering grain heads. Handle grain heads carefully during inspection to avoid disturbing adult sorghum midges. Other sampling methods can be used, such as placing a clear plastic bag over the sorghum head as trapping device for detecting adults.

Because they are relatively weak fliers and rely on wind currents to aid their dispersal, adult sorghum midges usually are most abundant along edges of sorghum fields. For this reason, inspect plants along field borders first, particularly those downwind of earlier flowering sorghum or johnsongrass. If no or few sorghum midges are found on sorghum grain heads along field edges, there should be little need to sample the entire field.

However, if you find more than one sorghum midge per flowering grain head in border areas of a sorghum field, inspect at least 40 more grain heads from the entire field (avoiding plants within 150 feet of field borders). Calculate the average number of sorghum midge per flowering grain head. Sample at least 20 flowering grain heads for each 20 acres in a field.

Base the need for insecticide treatment on the number of adult sorghum midges per flowering grain head after at least 20 percent of the grain heads in a field are flowering.

Insecticide residues should effectively suppress sorghum midges 1 to 2 days after treatment. However, if adults still are present 3 days after the first application of insecticide, immediately apply a second insecticide treatment. Three insecticide applications at 3-day intervals may be justified if yield potential is high and sorghum midges exceed the economic injury level. (See table below)

Table 1. Economic injury levels based on numbers of adult sorghum midge per flowering grain head of a susceptible sorghum head.

Sorghum Head-Feeding Bugs

Reports of stink bugs in grain sorghum were received during the past week from a few people. For the record, several species of true bugs, primarily stink bugs, may move in relatively large numbers from alternate host plants into sorghum during kernel development. Bugs infesting sorghum in our area include rice stink bug, southern green stink bug, brown stink bug, red-shouldered stink bug and the leaf footed bug.

Grain head-feeding bugs tend to congregate on sorghum grain heads and sometimes within areas of a field. Use the beat-bucket technique to estimate abundance. Shake sorghum heads vigorously into a 5-gallon bucket, where bugs can be seen and counted more easily. However, adult bugs will fly from the sampled plant or the bucket. Count those that fly from sorghum grain heads or from the bucket and those on plant leaves. To determine the profitability of controlling an infestation, see the tables listed below.

Table 2. Economic injury level based on number of rice stink bugs per sorghum grain head beginning at the soft-dough stage of kernel development.

Table 3. Economic injury level based on number of adult southern green stink bugs, brown stink bugs and leaf footed bugs per sorghum grain head beginning at the milk stage of kernel development.

Table 4. Economic injury level based on number of adult southern green stink bugs, brown stink bugs and leaf footed bugs per sorghum grain head beginning at the soft-dough stage of kernel development.

Did You Know

The Texas legislature passed House Bill 190 early in 1899, and F.W. Mally was appointed as the first State Entomologist, primarily to direct boll weevil research. This position came to fruition mainly by growers representing powerful families in the prosperous Brazos River region pressuring their state representatives to take action immediately.

The text of House Bill 190, directing the Agricultural and Mechanical College of Texas to establish the State Entomologist position, was as follows-

Be it Enacted by the legislature of the State of Texas:
Section 1, Article 1. That the president and board of directors of the Agricultural and Mechanical College of Texas, are hereby authorized and directed to employ an expert entomologist, one or more as may be deemed necessary, whose duty it shall be to devise, if possible, means of destroying the Mexican boll worm [sic], caterpillarsharpshooter, chinch bug, peach worm, and other insect pests, and to perform the duties of professor of entomology in the Agricultural and Mechanical College of Texas.

Section 2. The sum of five thousand dollars is hereby appropriated out of any money in the State Treasury, not otherwise appropriated, for the purpose of putting this act into effect.

Section 3. On account of the great destruction of the cotton and peach crop over sections of the state, and the menace to, and certain destruction of the entire cotton and peach crop of the state, unless the evil be promptly checked, an emergency and imperative necessity exists requiring the suspension of the constitutional clause requiring bills to be read on three several days, and the same is hereby suspended and that this act take effect from and after the date of its passage.

Looking back with a few years of hindsight, Hinds (1909) wrote, "as soon as the weevil entered Texas it became apparent that investigation of methods for its control constituted a national, rather than a state problem. An investigation by L.O. Howard, Chief of the Bureau of Entomology, immediately after receipt of the news of the presence of the boll weevil at Brownsville, showed clearly the great damage that threatened the Cotton Belt. The Department has repeatedly called attention to the fact that it was exceedingly unfortunate that no steps were taken to exterminate the weevil at the time of its first occurrence. The matter was brought to the attention of the State of Texas, but the authorities did not take action for the reason that the powers of damage of the pest had not become demonstrated as they have in recent years. An expenditure of perhaps $20,000 would have enabled the authorities to eradicate the insect completely and thus would have prevented the principal cotton producing portions of the country." (Source: Boll Weevil Eradication In The United States Through 1999, Number Six of the Cotton Foundation Reference Book Series)