Articles
A WHITEFLY TRANSMITTED VIRUS CAUSING MUSKMELON YELLOWS IN FRANCE
The symptoms appear as a typical interveinal yellowing of the older leaves ; characteristic pinpoint chlorotic spots develop on the younger leaves with greasy flecks on the lower surface of the leaves.
Yield may be seriously reduced.
Long flexuous and labile particles (approximatively 1 0000 nm) are detected with difficulty in dip preparations from such plants.
The virus is not transmissible mechanically and not by aphid but can be transferred by the greenhouse whitefly Trialeurodes vaporariorum from muskmelon to muskmelon.
The virus is also transmitted by whitefly to cucumber causing interveinal yellowing of the leaves.
The observations of thin sections prepared from artificially infected muskmelon and cucumber revealed that long flexuous particles are present in the phloem parenchyma cells and companion cells but not in epidermal and mesophyll cells.
Small vesicles containing fibrous material and amorphous granular structures are present in the infected cells.
From these data, the yellowing disease of muskmelon can be considered as very close to the "Cucumber yellows" described in Japan.
The relationship with the whitefly transmitted "Lettuce pseudo-yellows" which induce very similar yellowing on cucumber will be discussed.