Methyl bromide alternatives for bell pepper ( Capsicum annuum) and cucumber ( Cucumis sativus) rotations

Two field trials were conducted to determine the effect of soil fumigant and herbicide combinations as potential alternatives for methyl bromide (MBr) in bell pepper–cucumber rotations. For the first bell pepper–cucumber trial, fumigant levels were a non-treated control, MBr+chloropicrin (Pic) (67/33%, respectively) at a rate of 400 kg/ha, Pic at 400 kg/ha, metam sodium (MNa) at 945 l/ha, 1,3-dichloropropene (1,3-D)+Pic (83/17%, respectively) at 330 l/ha, and anhydrous ammonia (ANH 4) at 300 l/ha. For the second bell pepper–cucumber trial, fumigants levels were the same, except that ANH 4 was substituted by 1,3-D+Pic (65/35%, respectively) at 330 l a.i./ha. Fumigants were only applied during the bell pepper seasons. Herbicides used were napropamide at 4.50 kg/ha, metolachlor at 2.25 kg/ha, pebulate at 4.50 kg/ha, in addition to an untreated check. Applied herbicides did not interact with fumigants and had excellent control of goosegrass ( Eleusine indica L.), southern crabgrass ( Digitaria ciliaris L.) and smooth pigweed ( Amaranthus hybridus L.), but only poor to fair control of purple nutsedge ( Cyperus rotundus L.). The fumigants 1,3-D+17% Pic, MNa, and Pic had reduced nematode root galling compared with the unchecked control. All fumigants tested for bell pepper, except ANH 4, successfully showed significant residual effects for cucumbers in the same plots. In most cases, 1,3-D+17% Pic, and Pic were comparable to MBr.