Ba. Bailey et al., Formulations of Fusarium oxysporum f.sp. erythroxyli for biocontrol of Erythroxylum coca var. coca, WEED SCI, 46(6), 1998, pp. 682-689
Formulations of Fusarium oxysporum Schlechtend:Fr. f.sp. erythroxyli isolat
e EN-4, pathogenic to Erythroxylum coca var, coca (coca) were evaluated in
greenhouse and field studies to determine their relative ability to enhance
pathogen populations in the soil or cause disease in coca. The formulation
s rice-alginate prill, Pesta, and CG were most thoroughly tested and are pr
oducts of three formulation processes. The formulations were applied in the
greenhouse and field at 33.6 kg ha(-1). Ail the formulations tested enhanc
ed the population of EN-4 in the soil during greenhouse (> 6 wk) and field
(> 7 mo) experiments. EN-4 was present in the upper 1 cm of formulation-tre
ated soil at > 200-fold higher populations than established below a depth o
f 7 to 10 cm in both greenhouse and field experiments. This population dist
ribution was maintained throughout the 7-mo sampling period for field exper
iments. The enhanced soil populations of EN-4 were associated with an incre
ase in root colonization by the pathogen EN-4 in the field 5 to 7 mo after
treatment. The formulated F. oxysporum began to have a significant effect o
n plant death 100 to 200 d after application in two of three field experime
nts, based on repeated measures analysis. The various formulations rested t
ended to establish similar pathogen populations in soil and subsequently ca
used similar levels of disease. The primary factors influencing formulation
performance may be environmental, since inoculum production is dependent o
n sporulation of the formulation, which, although rapid, may continue over
several weeks subsequent to application.