Journal of Nematology (2005) 37, p. 371 (Gilreath et al.)

J.P. Gilreath, B.M. Santos and J.W. Noling (2005)
The vagaries of alternatives to methyl bromide for nutsedge control
Journal of Nematology 37 (3), 371-371
44th Annual Meeting, Society of Nematologists, Fort Lauderdale, Florida, 9-13 July, 2005
Abstract: Control of yellow and purple nutsedge (Cyperus esculentus and C. rotundus, respectively) has been the most difficult task for all alternatives to methyl bromide tested to date. Nutsedges are difficult to control due to the rapid formation of tuber chains with apical dominance, the dense nature of those tubers, tuber dormancy factors, and the ability to survive under long term adverse conditions. Research focused on herbicides to be used in combination with alternative fumigants when it was determined that none of the alternatives provided consistent control. Pebulate (Tillam herbicide) in combination with 1,3-D + chloropicrin was selected as the most likely replacement for methyl bromide for mulched tomato production. Unfortunately, pebulate was not re-registered, thus setting back the search for alternatives for tomato. For other mulched vegetables and cut flowers, there are even fewer herbicide options to consider and manufacturers are not enthusiastic about pursuing registration of herbicides for minor use crops. Additionally, herbicide residues can be a problem and plant back restrictions exist on some labels. Current emphasis is on screening new fumigants and attempting to overcome the limitations of existing fumigants. In particular, we have investigated ways to improve upon fumigant delivery, either with new equipment, such as the Mirusso-Yetter Avenger coulter rig, or refinements in use of existing procedures, such as improved understanding of water and fumigant movement when delivered by drip irrigation. Another approach has been to re-examine rates for some fumigants; suggested rates for propylene oxide were 30 to 40 gal/acre but good control of nutsedge required 80 gal/acre. Studies with virtually impermeable films (VIF) and a high barrier metalized film indicate that rates either can be reduced to as low as 25% of normal for methyl bromide or standard rates with these barrier films can impart considerable improvement in nutsedge control (e.g. iodomethane and 1,3-D + chloropicrin). Most tomato producers in Florida will be trying a one-half rate of methyl bromide in combination with metalized film on part of their acreage this fall with some producers commiting more than one-half of their crop to this technique. Lower rates are technically feasible, but difficult for growers to deliver with the degree of uniformity required for consistent efficacy.

Research topic(s) for pests/diseases/weeds:
control - general

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Cyperus rotundus (weed)	Tomato (Solanum lycopersicum)	U.S.A. (SE)
	Cyperus esculentus (weed)	Tomato (Solanum lycopersicum)	U.S.A. (SE)