Field Guide of Discovery-based Exercises for - Aseanipm ...

Exercise No. 5.15 205
BACTERIAL WILT MANAGEMENT IN ORGANICALLY-
GROWN SOLANACEOUS VEGETABLES THROUGH
BIO-FUMIGATION
BaCKGroUND aND raTIoNalE
Bacterial wilt, caused by Ralstonia solanacearum, is a
serious disease of many solanaceous vegetables (e.g.,
tomato, eggplant, pepper, and potato) that can reduce yield
and income of farmers tremendously. Infected plants in
field appear in patches and first symptom is wilting of
younger leaves or slight yellowing of older leaves. The
bacteria can survive in soil for a long time and can infect
many plants including weeds. The bacteria are spread
through infected seedlings, contaminated irrigation
water, farm implements, and animals. Some practices to
300
Field Guide of Discovery-based Exercises for Organic Vegetable Production
when is this exercise most
appropriate?
ɶ In FFS, TOT, and VST
sessions, prior to or during
land preparation and
as component of topic
on ‘Integrated Disease
Management’; and
ɶ When farmers want to learn
innovative practices in using
crop wastes as bio-fumigants
for management of bacterial
wilt disease in organicallygrown
solanaceous
vegetables.
minimize bacterial wilt are: (a) use of resistant varieties; (b) crop rotation with rice, corn, beans, or
crucifers; (c) removal of infected plants from the field; (d) solarization; and (e) bio-fumigation.
Bio-fumigation is a breakthrough in bacterial wilt management. This refers to suppression of soil
pests and diseases by toxic substances such as isothiocyanates (ITCs) produced by brassica green
manure following incorporation into soil. In farmers’ field trials, use of broccoli green manure
reduced bacterial wilt incidence by 52-81%, mustard by 29-61% and radish by 27-70% across
locations. The efficacy of bio-fumigation is influenced by soil texture as shown by reduction of R.
solanacearum population ranging from 74-87% in clay loam soil compared to 96% to almost 100%
population reduction in sandy loam soil.
Brassica wastes like stems and leaves of broccoli, cabbage, and cauliflower are available in large
quantities in areas where these crops are grown extensively (e.g., Benguet and Mountain Province)
and are considered a problem in garbage disposal or solid waste management. These waste materials
can be used as bio-fumigants to reduce bacterial wilt incidence of solanaceous crops like potato,
tomato, and eggplant in areas where bacterial wilt is a problem. The practice of bio-fumigation can
also help alleviate problem in solid waste management.
205 Bayot, R.G., V.P. Justo, and J.P. Dangan. 2005. Management of tomato bacterial wilt using bio-fumigation. Paper presented during a Workshop on
Integrated Production and Pest Management in Processing Tomato: Issues and Prospects held on July 2005 at Laoag City, Ilocos Norte, Philippines.
11p.