False mealy dew causes dirty taint, whitish stains on a surface of leaves of onions. False mealy dew is fungoid disease. False mealy dew extends by ergots (a taint on affected leaves) with rain drops, a wind. Having got on a plant, ergots sprout and take root into a tissue. Leaves prematurely are dried up.
Mealy dew develops in damp weather more strongly. Infection sources are the infected perennial onions, the vegetative rests.
In struggle against false mealy dew it is important to improve a planting stock:
- The infection perishes at warming up of bulbs within 8 hours at temperature 40 ° (autumn),
- It is necessary periodically to look through crops and to destroy sick plants,
- Pericarps are sprayed with 1% bordeaux, adding paste to it, for the best fixation on plants.