FIG. 1. Test results ofJMS stylet oil on plots of squash


uninoculated in untreated plots (Table 2). Table 2 also suggests
that irrespective of the presence of viruliferous aphids and/or in-
field inoculum, the oil application affords a 6.8-fold reduction in
disease spread at the upper limit, and a two-fold reduction at the
lower limit (P = 0.05).


 40



C-
B 30



 20




 10




 O 1 2 3 4 5 6
 (weeks)


 (B) No Oil Inoculated
 (D) No Oil, Uninoculated
 (A) Oil, Uninoculated
 (C) Oil, inoculated


VOL. XX-PROCEEDINGS of the CARIBBEAN FOOD CROPS SOCIETY


 The pattern of spread of the disease is different between sprayed
and unsprayed plots (Fig. 1). There is a more gradual spread in
those treated. The leveling off of curves (a) and (c) between six and
seven weeks indicates no further disease spread at that time, while
within the same period, curves (b) and (d) had moderate increases.
This observation indicates the similarity in the pattern of disease
spread whether or not a field was inoculated, and also a similarity
in the pattern of the suppression of spread by the oil treatment
whether or not some plants within a field were previously infected
(Fig. 1).
 The levels of disease control obtained with JMS stylet oil in this
study compare favourably with those of other investigators using
this oil to control non-persistent aphid-borne virus diseases in crops
(Bradley, 1963; Zitter and Ozaki, 1978; Simons and Zitter, 1981).



References
 1. Bradley, R.H.E. 1963. Some ways in which a parafin oil impedes aphid
 transmission of potato virus. Can. J. Microbiol. 9:369-380.
 2. Franki, R.I.B. 1972. Purification of viruses. In: Principles and Techniques of
 Plant Virology by Kado and Agrawal. Van Nostrand Reinhold Co., Toronto, Lon-
 don.
 3. Simons, J.N., and T.A. Zitter. 1981. Use of oils to control aphid-borne
 viruses.
 4. Smith, K.M. 1972. A textbook of plant virus diseases. 3rd Ed. Longman
 Group Ltd., London.
 5. Thomas, Omer S. Lloyd. 1980. Mosaic disease on hot peppers. FAO Plant
Prot. Bull. 28(3):118.
 6. Thomas, Omer S. Lloyd. 1981a. Virus diseases of cultivated plants in Mont-
serrat. Trop. Pest Mgmt. 27(4):461-464.
 7. Thomas, Omer S. Lloyd. 1981b. A survey of virus diseases of economic
plants in Montserrat. Proc. 1st Mtg. P1. Prot. in the Carib., Kingston, Jamaica. pp.
155-160.
 8. Turner, M.P., and R. Stace-Smith. 1979. Plant virus disease survey of
Jamaica. FAO P1. Prot. Bull. 27(1).
 9. Zitter, T.A., and H.Y. Ozaki. 1978. Aphid-borne vegetable virus control
with oil sprays. Proc. Fla. State Hort. Soc. 91:281-289.


r (D)





(C)


295