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Title: EFFECTS OF THE PLANT GROWTH REGULATOR MEPIQUAT CHLORIDE ON SILVERLEAF WHITEFLY (HOMOPTERA: ALEYRODIDAE) INFESTATIONS ON COTTON

Author
item Flint, Hollis
item Leggett, Joseph
item Elhoff, Leanne
item Parks, Nancy
item DAVIDSON, ELIZABETH - ARIZONA STATE UNIVERSITY

Submitted to: Journal of Entomological Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/1/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: Cotton growers sometimes use a plant growth regulator to slow excessive growth of plants and increase yield. Pix is a commercial growth regulator that suppresses plant cell enlargement, producing a smaller plant with thicker leaves. We observed that Pix-treated plants in the greenhouse also had reduced infestations of whiteflies. Whiteflies are a significant pest of cotton as well as vegetable and ornamental crops. We conducted three field plot tests of cotton treated with Pix to see if the reduced infestations of whiteflies seen in the greenhouse could be obtained under field conditions. The effects of Pix on plant growth were obtained but reductions in whitefly infestations were not. We found that Pix-treated plants in the greenhouse had reduced water stress compared to untreated plants but treated plants in the field were the same as untreated plants. whiteflies avoid plants with reduced water stress when they have a choice as in our greenhouse studies.

Technical Abstract: Plants of cotton, gossypium hirsutum L., were treated with the mepiquat chloride (PixTM) in greenhouse and field plot tests to determine its effect on infestations of the silverleaf whitefly, Bemisia argentifolii Bellows and Perring. In the greenhouse, Pix- treated plants were significantly shorter and had significantly thicker leaves than untreated plants by the end of the second week following application. Some Pix treatments caused significant reductions in resting adults and in nymphs on leaves by the third week following application. Most of the Pix treatments caused significant reductions in adults, eggs and nymphs on leaves by the fourth week of the test. In a separate test, leaf water potentials were equal for Pix-treated and well-watered plants and those leaf water potentials were significantly lower than for water-stressed and control plants. Pix-treated plants in two field plot tests showed the same changes in plant morphology seen in Pix-treated plants in the greenhouse. However, leaf water potentials were the same as in untreated plants and no reductions in whitefly infestations were found. Pix-treated plants in a third field plot test showed no changes in plant morphology or in whitefly infestations. The differences in results for greenhouse and field plot tests may be caused by reduced leaf water potentials in Pix- treated plants under greenhouse conditions.