approximately 6 inches apart. For effective results, one must treat 50% of the bed, which would

require two chisels per bed.

 Due to the water solubility of Vapam, it is also labelled for application through overhead

irrigation. A study conducted by Sumner (1988) found increased efficacy against Rhizoctonia

soani and Pythium sp. when metham sodium was applied via overhead irrigation, as compared

to chisel application for a fall crop of turnip, kale, mustard and collard. However, reduced

control of root diseases and decreased plant stand in the spring crops of snap bean, okra,

cucumber, tomato, and pepper were also observed. Increasing application rates resulted in

improved control of soilborne diseases such as Pythium WS., Fusarium Wp. and saprophytic

fungi.

 Chemical application of Vapam via drip irrigation is a form of chemigation (Haman et.

al., 1990). This method requires that the metham sodium be premixed prior to injection and

continuously supplied at specific locations for a period of time. There are several factors that

influence chemigation for pest control, including emitter spacing, type and length of irrigation

tubing, openings in the plastic which can allow diffusion into the atmosphere, and

soil/environmental conditions (Noling, 1993d). Overman et al., (1987) compared methyl

bromide (67%) plus chloropicrin (33%) injected via shanks 30 cm apart prior to plastic

application, to metham sodium injected via one drip line per bed. This study was conducted for

three seasons and found that yields for 'Sunny' tomato variety increased for both treatments,

however, by the third season yields were collected only from the methyl bromide-chloropicrin

plot. The area treated with metham sodium was desiccated with Fusarium wilt and root knot

nematode.