Submitted to: Western Society of Weed Science Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: November 28, 2007
Publication Date: March 13, 2008
Citation: Hanson, B.D. Evaluation of Pre-emergence Herbicides in Stone Fruit Field Nurseries[abstract]. Proc. Western Soc. Weed Sci. 61:13. Interpretive Summary: This report presents research data on herbicide screening in two almond tree nursery trials conducted from 2006 to 2007. Weed control and nursery crop safety with several labeled and unlabeled herbicides are discussed. Several promising herbicides including dithiopyr, flumioxazin, and rimsulfuron were identified and several others such as sulfentrazone with poor crop safety were eliminated from future consideration. This type of research is needed to identify additional weed control strategies in an industry that currently relies heavily on preplant fumigation with methyl bromide, extensive tillage, and hand weeding for adequate weed control.
Technical Abstract: Open field production of fruit and nut tree nursery stock depends upon preplant soil fumigation, extensive tillage, and hand labor throughout the growing season for adequate weed control. Because methyl bromide, the favored fumigant, is being phased out due to environmental concerns and the costs of both fuel and labor continue to rise, herbicides are likely to become a more important weed management tool in the tree nursery industry. Two trials were conducted to evaluate weed control and crop safety with several herbicides applied following fumigation with methyl bromide or 1,3-dichloropropene in central California stonefruit nurseries. PRE and POST-directed applications of several labeled and unlabeled materials were applied in a band over seeded peach rootstock or applied after emergence with a drop-nozzle spray boom. Crop productivity and weed control were monitored throughout the one year growing season. PRE oryzalin and dithiopyr provided the best weed control with very little crop injury. PRE flumioxazin, rimsulfuron, and sulfentrazone did not have adequate crop safety at the rate and timing tested. However, POST-directed applications of flumioxazin and rimsulfuron were much safer to the peach/almond crops and should be evaluated in future trials. Additional herbicides and application techniques are needed to find acceptable, safe control of weeds such as California burclover, common mallow, and redstem filaree, which often are poorly control with preplant fumigation in tree nurseries.