Fv. Sances et Er. Ingham, CONVENTIONAL AND ORGANIC ALTERNATIVES TO METHYL-BROMIDE ON CALIFORNIASTRAWBERRIES, Compost science & utilization, 5(2), 1997, pp. 23-37
A study was conducted in a commercial strawberry planting on the Calif
ornia central coast to evaluate the relative efficacy of chemical and
organic alternatives to methyl bromide fumigation. The three chemical
alternatives included Telone/Chloropicrin 70/30, Basamid, and Metam so
dium. Organic alternatives included addition of broccoli residues, spe
nt mushroom compost, and a combination of both broccoli and spent mush
room compost. AU treatments were compared to standard methyl bromide/c
hloropicrin 75/25. Weeding costs were five-fold greater in organic tre
atments than in chemical fumigant treatments and were not statisticall
y different from untreated controls. The weed species in the organic t
reatments were significantly different than in the untreated or the ch
emical fumigant treatments, suggesting that these weeds were in the ad
ded organic material. Strawberry yields were highest in the methyl bro
mide/ chloropicrin, Basamid and Telone/chloropicrin treatments. Strawb
erry yields among the organic treatments were not statistically differ
ent from the untreated control. Soil microbial biomass measurements an
d strawberry root pathology indicated that a single application of the
se particular organic amendments were inadequate in significantly incr
easing soil food web diversity on this previously fumigated soil to a
point where strawberry pathogens could be suppressed to commercially a
cceptable levels. These results suggest that previously fumigated soil
that has been depleted of Vesicular Arbuscular Mycorrhizal (VAM) fung
al colonization and other beneficial microbiota require additional rec
onditioning before the soil would be suitable for commercial strawberr
y production, given the highly pathogen susceptible cultivars commonly
grown in California.