ARS | Publication request: Biological control of Cucurbita pepo var texana (Texas gourd) in cotton (Gossypium hirsutum) with the fungus Fusarium solani f sp Cucurbitae

Submitted to: Pest Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 20, 2010
Publication Date: September 3, 2011
Citation: Boyette, C.D., Bryson, C.T., Hoagland, R.E. 2011. Biological control of Cucurbita pepo var. texana (Texas gourd) in cotton (Gossypium hirsutum) with the fungus Fusarium solani f. sp. Cucurbitae. Pest Technology. 5(1):97-101.

Interpretive Summary: Texas gourd is an escaped ornamental that is becoming a weed problem in soybean and cotton in localized areas of the mid-south. It is especially difficult to control in cotton because most herbicides that are effective in controlling this weed are not registered for use in cotton. Solid (cornmeal-sand medium [CMS] and wheat-gluten [‘Pesta’]) and liquid (water, or unrefined corn oil with surfactant) formulations of the fungus Fusarium solani f. sp. cucurbitae were evaluated pre-emergence (PRE) and post-emergence (POE) for weed control. We found that dew was not required to achieve optimal levels of weed control with either the PRE-CMS or ‘Pesta’ formulations or with POE-corn oil/surfactant. In field tests, PRE applications of CMS and Pesta granules controlled 90-94 percent of the weeds. POE applications of FSC formulated in corn oil/surfactant were equally effective in controlling Texas gourd. Since the range of Texas gourd appears to be increasing, and chemicals that can control the weed are being removed from the market due to loss of EPA registration, there may be a potential to utilize this pathogen as a bioherbicide for controlling this troublesome weed.

Technical Abstract: Experiments were conducted to evaluate various formulations and application methods of the fungus Fusarium solani f. sp. cucurbitae (FSC) for controlling Texas gourd (Cucurbita pepo var. texana) in cotton (Gosssypium hirsutum). In greenhouse tests, Texas gourd was controlled 93% and 96%, respectively, with preemergence (PRE) applications of FSC-infested cornmeal/sand medium (CMS) and FSC-wheat flour/kaolin (Pesta) granules. Postemergence (POE) applications of CMS or Pesta granular formulations were less effective overall. However, >90% control of Texas gourd was achieved with POE applications of FSC spores formulated in an emulsion consisting of 25% unrefined corn oil and 0.2% Silwet L-77 surfactant. Dew was not required to achieve optimal levels of weed control with either the PRE granular formulations or with POE corn oil/surfactant applications. In field tests, PRE applications of FSC-infested CMS and FSC-Pesta granules controlled 90-94% of the weeds. POE applications of FSC formulated in corn oil/surfactant were equally efficacious in controlling Texas gourd.