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

Exercise No. 5.12 196
UPROOTING AND PROPER DISPOSAL AS A
MANAGEMENT STRATEGY AGAINST TYMO VIRUS
DISEASE OF ORGANICALLY-GROWN CHAYOTE
BaCKGroUND aND raTIoNalE
The most common symptoms and effects exhibited by
chayote plant with tymo virus disease are overgrowths,
stunting, yellowing, curling, and mottling. Collectively,
these symptoms are locally known as agparparya or
parparya. The tymo virus disease is very infectious and
can be transmitted easily from diseased to healthy plants
by mere contact or by animals, men, and machines. It
is also suspected that tymo virus can be spread by some
insects.
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Field Guide of Discovery-based Exercises for Organic Vegetable Production
when is this exercise most
appropriate?
ɶ In FFS, TOT, and VST
sessions, when early
symptoms of tymo virus
disease are observed on
chayote planted in learning
and adjoining fields; and
ɶ When organic farmers want
to learn from other farmers
proper uprooting and
disposal of chayote plants
infected with tymo virus
disease.
Uprooting or removal of entire diseased plant is one common control measure. Diseased plants
are systematically removed from a plant population in order to reduce the amount of inoculum to
which chayote crop will be exposed. Uprooting is a very sound practice in disease management,
particularly when tymo virus disease is just starting to build up. In severe cases, complete
destruction or uprooting of entire chayote population is an effective way of eradicating tymo virus
disease 197 . In the highlands, some chayote farmers practice uprooting tymo virus-infected plants in
their fields. Unfortunately, they lack knowledge on the proper disposal of uprooted infected plants.
Many organic farmers, however, know that uprooting and proper disposal of virus-infected plants is
the most practical and effective management strategy against tymo virus disease.
Through time, organic farmers that are more enterprising in the Cordilleras have evolved more
effective strategies that can complement uprooting and proper disposal for better tymo virus disease
management. Through participatory, discovery-based, and experiential learning approaches in
farmer field schools (FFSs), these strategies can be further improved. The foregoing exercise was
designed to achieve this purpose.
196 Adapted from Callo, Jr., D.P., L.B. Teofilo, and H.A. Tauli (eds). 2002. Field Guide of Discovery-based Exercises for Vegetable IPM, Volume II. SEAMEO
Regional Center for Graduate Study and Research in Agriculture (SEARCA), Los Baños, Laguna, Philippines. pp250-252.
197 Quebral, F.C. 1988. What one should know about plant diseases. University of the Philippines Los Baños, College, Laguna, Philippines. pp18-20.