In rainy cold weather onions often get sick peronosporozy or false mealy dew. If urgently not to take measures for elimination of this artful disease, then the harvest of onions will be lost.
Why onions are ill peronosporozy?
The mycelium settles on the weakened plants. The landings of onions which are grown up on insufficiently the lit and blown places, first of all are surprised this disease. The onions plants which are too overfed by nitrogen fertilizers also are in risk group. Cold rainy weather provokes this disease. Non-compliance with crop rotation - one of the main reasons of appearance of disease.
How does look peronosporoz?
The mycelium strikes onions feather. Green leaves become covered by gray-violet spots which blur on all feather.
Further leaves take the lurid becoming wet form and droop.
The mycelium from sheet feather passes to ""eating"" of bulb. The injuriousness from peronosporoz, especially in cold rainy weather, is extremely big and dangerous. The yield loss can be up to 50%. But contamination of the site is even more dangerous by fungal spores which will remain to winter and will bring troubles next year and to other cultures.
What should be undertaken urgently?
If defeats minimum, then it is enough to carry out processings at an interval of 7-10 days the medicines containing copper. It is all the known Bordeaux mix, hy, kuproksat, kuprolux, ordan. Modern fungicides the profit gold, ridomit gold effectively stop disease. It is possible to opudrit plants wood ashes, spending about one glass for 1 sq.m.
Fertilizing by nitrogen fertilizers quickly stops and gives to onions plants only phosphorus-potassium.
At air rise of temperature from above 27-28os the mycelium stops the attacks.
From national effective methods it is possible to apply spraying by the sour milk diluted with water, serum. The infusion of nettle, fresh grass kept several days also stops spread of disease.
Important. Onions which is grown up on green feather for food cannot be processed chemical medicines.