Soil fumigant and herbicide combinations for soilborne pest control in caladium

摘要

Soil fumigant and herbicide combinations were investigated as replacements for methyl bromide in 'Red Frill' caladium (Caladium X hortulanum Birdsey) tuber production in 1998 on a sandy muck soil at a commercial farm in Lake Placid, FL. Treatments consisted of methyl bromide:chloropicrin (90/10 percent), 1,3-dichloropropene + chloropicrin, metham + chloropicrin and a nontreated control. Plots treated with 1,3-dichloropropene or metham received soil surface sprays of metolachlor at planting and oryzalin about 7 weeks later. Plots treated with methyl bromide received only oryzalin, whereas the nontreated controls received no herbicide during the experiment and were handweeded as needed. Initial plant stand was not affected by treatment. Plant vigor was higher in methyl bromide treated plots on 30 July; but by 6 October plants were just as vigorous in plots treated with 1,3-dichloropropene + chloropicrin as they were in areas fumigated with methyl bromide. Early control of weeds was good with those treatments which received metolachlor, but treatment with methyl bromide alone allowed an early infestation of crabgrass (Digitaria ciliaris (Retz.) Koel.) and pigweed (Amaranthus viridis L.). Application of oryzalin provided good weed control for all fumigant- treated plots into mid fall, after which time the grower was not concerned about weed control. Root-knot nematodes (Meloidogyne sp.) were not found in the tubers from any fumigated plot at harvest nor in soil samples from any plot during the season. Fusarium sp. was found in all of the tubers at planting and at harvest. Although Erwinia, Fusarium, Pythium and Rhizoctonia were found in most of the tubers, no differences were found in incidence of infestation due to any treatment. There was no difference in tuber production for any size grade, except jumbo; significantly more jumbo tubers were produced in plots treated with 1,3-dichloropropene + chloropicrin with metolachlor at planting followed by oryzalin in mid summer. Chloropicrin + 1,3-dichloropropene out produced all other fumigants for jumbos and no difference was found in jumbo production with methyl bromide or metham + chloropicrin or where no fumigant or herbicide was applied. No differences in the tuber production index were evident with any treatment.