Controlling Viruses In Lettuce

In South Africa, two viruses are a particular threat to lettuce: tomato spotted wilt (TSWV) and lettuce mosaic virus (LMV). Both can be highly destructive and spread quickly via vectors such as sucking insects and thrips.

- Bill Kerr

Lettuce mosaic virus shows downy mildew on the lower leaves.

One of these vectors, the green peach aphid, frequently attacks lettuce, but can be controlled effectively by ladybird beetles. For this reason, many farmers do not spray young lettuce for this pest if there is only a small population and ladybird beetles are present. If any virus is found at the same time, however, you will need to spray, even if there is only a small population of aphids.

ELIMINATE ALL BROADLEAF WEEDS ON THE VERGES OF THE LAND

TSWV is spread by thrips, which are not usually noticed on the crop.