Multi-species weed spatial variability and site-specific management maps in cultivated sunflower

10 pages; 2 tables: 3 figures

Geostatistical techniques were used to describe and mar weed spatial distribution in two sunflower fields in Cabello and Monclova, southern Spain. Data from me study were used to design intermittent spraying strategies. Weed species, overall infestarían severity (15) index, and spatial distribution varied considerably between me two sites. Weed species displayed differences in spatial dependence regardless of 15. The 15 mapping of each single weed and of the overall infestarían was achieved by kriging, and site-specific application maps were then drawn based on the multi-species weed mar and the estimated economic mreshold (ET). Herbicide treatmenr was assumed to be needed for an overall 15 score of 2 or 3, and the infested "area exceeding me economic threshold" was determined. The overall weed-infested arca varied considerably between locations. About 99 and 38% of the total arca was moderately infested (15 ~ 2) at Monclova and Cabello, respectively. Therefore, if a given herbicide were applied just to the arcas exceeding the ET, a significant herbicide saving would be realized in Cabello but not in Monclova. A multi-species spatial analysis provides an opporrunity to make site-specific managemenr recommendations from a mar of me distribution of 15 of me total infestarían. Furrhermore, only in fields wim hardto- control weed species (e.g., nodding broomrape and corn caraway) would sitespecific herbicide application maps developed from total weed infesrations need to be complemented with targered sire-specific herbicide treatmenrs ro prevenr furrher spread of these species, alrhough rheir 15 mighr be low.

CICYT-FEDER projeet (lFD97-0049).

Peer reviewed