Betsy A. Anderson, USDA/ARS, ATRU, Biological Science Technician, IR-4 Specialist; Michael E. Reding, USDA/ARS, ATRU, Research Entomologist; Michael G. Klein, USDA/ARS, ATRU, Research Entomologist; and Charles R. Krause, USDA/ARS, ATRU, Plant Pathologist.
Phytotoxicity results are shown in Table 1. Most trials showed no phytotoxicity, although both formulations of the herbicide flumioxazin caused chlorosis and necrosis on the two plant species, Deutzia gracilis and Phalaris arundinacea (Ribbon-grass). The fungicide Bacillus subtilis caused necrotic leaf margins and spotting on Verbena canadensis and Impatiens hawkeri. Acibenzolar, a plant protectant, reduced flowering after the third and fourth treatments on Impatiens balsamina.
Efficacy data was not obtained in the insecticide container tests or the rhododendron field tests due to poor survival of grubs in control plants. The naturally infested field of hemlocks showed stunting from European chafer larval feeding and yielded efficacy data for the trichlorfon (e.g., Dylox) drench applications. The three Dylox treatment rates all had significantly fewer grub numbers than the untreated trees (the average number of grubs was 3.2 and 1.1 in the untreated controls and 1X rate of Dylox, respectively).
Nursery growers should let their pest control needs be known by submitting a request electronically from the IR-4 website:
or by calling Betsy Anderson, USDA/ARS, at 330-263-3898 or by e-mailing