T-Y IPM NEWS

news about integrated pest management in Terry and Yoakum counties
Scott A. Russell, EA-IPM
Telephone: (806) 637-4060
Mobile: (806) 893-1041
Fax: (806) 637-2588
E-Mail: sarussel@tamu.edu   http://lubbock.tamu.edu/ipm  
Vol. 3, No. 9
209 South Fifth Street, Brownfield, TX 79316
August 1, 2002

In this issue:
General Situation
Cotton Aphids

General Situation:
This week there have been no program fields requiring insecticide treatments. Generally worm numbers were down from last week, with few to no bollworm eggs being observed. Area fields would all benefit significantly from rainfall. Many area dryland fields (and even irrigated with weak water) are cutting out and blooming near the top. Irrigated fields which have not stressed are from 5 to 7 nodes above white flower (four nodes above white flower being physiological cutout). Although beneficial numbers are low overall, we are seeing more lacewing and lady beetle larvae where aphids are present. Economic worm infestations (8-10 medium sized worms) are being found in some peanut fields. Be careful not too be over zealous, as mites can become a problem later.

Cotton Aphids:
Cotton aphids can be found in many area fields. They are present regardless previous treatment histories. In spots they are beginning to build in the terminal, although confined to only a few plants in any one field.

We are seeing increased numbers of lacewing larvae and lady beetle larvae associated with these aphids. With the present heat and dry weather expect aphid numbers to continue to rise.
Aphids usually are

light yellow to dark green to almost black. The immature or nymphal stage looks like the adult stage, only smaller. Most adults do not have wings. Aphids usually are found on the undersides of leaves, on stems, in terminals and sometimes on fruit. Heavy and prolonged infestations can cause leaves to curl downward, older leaves to turn yellow and shed, squares and small bolls to shed and bolls to be reduced in size, resulting in incomplete fiber development.

Honeydew excreted by aphids can drop on fibers of open bolls. A black, sooty fungus sometimes develops on the honeydew deposits during wet periods. Fiber from such bolls is stained, sticky and of lower quality, resulting in difficult harvest, ginning and yarn spinning. Natural control by unfavorable weather, predators, parasites and pathogens can be effective in holding populations below damaging levels. Sometimes aphid numbers increase to moderate or heavy levels and then decline for no apparent reason.

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.
The Texas A&M University System, U.S. Department of Agriculture, and the Commissioners Courts of Texas Cooperating
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Management and decision making.
Fields should be scouted twice per week since rapid in-creases in aphid numbers can occur in a short time. A total of 60 leaves divided between the top, middle and lower portion of the plant should be sampled from plants across the field to determine actual infestation levels. Insecticidal control of cotton aphids should be delayed until infestations exceed 50 aphids per leaf.

Brant Baugh, Extension Agent - I.P.M., Lubbock County, recently provided the following test data.

Control of cotton aphids with various insecticides, RR2200, Rex Isom Farm, Idalou, Texas. 2000.

Average Number of Aphids per Leaf 1/
Treatment2/ 0 dpt 5 dpt % control3/ 9 dpt %
control
Intruder 70WP 1.1 oz 105.73a4/ 1.30c 99.59 0.30c 99.08
Intruder 70WP 2.3 oz 147.90a 3.35c 99.32 0.53c 98.96
Bidrin 8E
5.3 oz		 156.83a 142.47bc 64.19 4.57c 88.98
Bidrin 8E
8.0 oz		 163.40a 68.73c 84.80 2.07c 95.61
Centric 40WG 1.9 oz 112.20a 89.20bc 79.70 3.70c 91.91
Furadan 4F
8.0 oz		 97.03a 46.87c 86.66 3.13c 91.44
Provado 1.6F 3.8 oz 73.97a 148.33bc 28.77 12.93bc 40.37
UTC ------ 402.00a ------ 41.87ab ------
LSD (P=.10) NS 152.465 30.965
P>F 0.1431 0.0082 0.0324
1/ Average of total number of aphids on five top and bottom leaves per plot.
2/ Treatments were applied with a CO2 backpack sprayer at 40 psi and 15 GPM.
3/ Percent control was adjusted using Henderson's formula.
4/ Means in a column followed by the same letter are not significantly different by ANOVA (P = 0.10 LSD).

 

Although Furdan has a Section 18 for Cotton Aphids, there are several products which should work very well, cost comparable to Furdan, and not require the 14 day re-entry interval..

Suggested Insecticides for control of aphids in cotton:

Insecticide Formulated Amount per acre
Lorsban® 4E 8-32 oz
Bidrin® 8E 4-8 oz
Bidrin® 8E + Ovasyn® 1.5E 4-8 oz +
0.67-1.33 pt
Bidrin® 8E + Curacron® 8E 4-8 oz + 2-4 oz
Provado® 1.6F 3.75 oz
Trimax® 4F 1.5 oz
Lannate® 2.4 LV 12 oz
Parathion 8E 4-6 oz
Curacron® 8E 8 oz
Centric® 40 WG 2 oz

Remember, the only way to know if you need to treat, is get out there and look...

If you treat with Furdan, please be sure to notify your field hands, your consultant and the Texas Boll Weevil Eradication Foundation, Field Unit Supervisor for that field.


T-Y IPM News is a publication of the Texas Agricultural Extension Service IPM Program in Terry and Yoakum Counties.
Editor: Scott A. Russell
EA-IPM,
Terry & Yoakum Counties		 Production: Bea Pippin


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