Pest Management Guidelines
Special Weed Problems
(Reviewed 12/09, updated 6/12)
COMMON PURSLANE, JUNGLERICE, AND BARNYARDGRASS. These weeds are particular problems when a climate modification technique is used in early spring to promote early harvest. Halosulfuron (Sandea), applied preemergence, can provide good control of junglerice and some suppression of purslane. Bensulide is effective against these weeds, but inadequate soil incorporation has frequently resulted in poor levels of control. Avoid growing cucurbit crops for early harvest in fields heavily infested with these weeds.
NUTSEDGE. Nutsedge is a serious weed in spring- and summer-planted crops. Yellow and purple nutsedge are perennial weeds that reproduce from underground tubers and can survive for several years in soil. Each tuber contains several buds that are capable of producing plants. One or more buds on the tuber germinate at a time to form new plants; however, if a bud or plant is destroyed by cultivation or an herbicide, then a new bud is activated. Halosulfuron (Sandea), applied postemergence, provides good to excellent control of nutsedge and is labeled for all cucurbit crops. In some cucurbit crops (watermelon and summer squash), however, only directed applications are permitted and nutsedge can remain a problem in the seed line. A banded application of metam sodium, centered on the seed line, will help suppress yellow nutsedge. Other options include rotating to crops where effective herbicide and cultural control methods can be used or continuous cultivation during a summer fallow period. Deep plowing (9 to 10 inches) with a moldboard plow before listing the beds can bury nutsedge tubers to a sufficient depth so that their emergence is slowed down during the crop establishment period.
FIELD BINDWEED. Field bindweed is a widely distributed perennial weed that can reduce cucurbit yields. Glyphosate (Roundup), paraquat (Gramoxone Inteon), and trifluralin (Treflan) all provide partial control of this weed. This weed can be controlled with a postharvest application of glyphosate or during the fallow season using glyphosate and cultivation; or, deep plow using chisel plows on reclamation blades at depths of 16 inches in dry soil during the summer before planting.
UC IPM Pest Management Guidelines: Cucurbits
WeedsC. S. Stoddard, UC Cooperative Extension, Merced & Madera counties
Acknowledgment for contributions to Weeds:C. E. Bell, UC Cooperative Extension, San Diego County
W. T. Lanini, Plant Sciences and Weed Science, UC Davis