Plantwise Factsheets for Farmers
"Burned tip" or downy mildew in onions
Recognize the problem
mildew is a fungus that affects all stages of the onion plant. It produces burns
and coffee-colored spots on the leaves, generally starting at the tips and moving
downwards. At the beginning, it can be confused with injuries caused by
chemicals and mechanical damage.
attack may reduce the yields and the product quality almost completely.
fungus is transmitted through spores that can survive on the soil, attacking
new crops. It can be spread by the wind and contaminated seeds. This disease
best develops under humid and cool conditions. During the rainy period,
prevention and control measures are necessary.
fertilization conditions with bokashi or another organic fertilizer to revive
the soil and maintain good nutrition of plants
- Add ash
or lime to the soil
- Sow during
hot and dry periods, but be careful because this type of weather is favorable
for the growth of thrips, a pest that is harmful to onions
apply natural products that control harmful fungi such as Bacillus subtilis, Saccharomyces
sp., Mimosa tenuiflora extract ("Revancha"),
and Trichoderma; make applications on
the soil and the leaves at 400 grams per hectare
the crop clean, destroying the crop residues
apply Azoxystrobin (e.g. Amistar) at a dose of 67 grams in 200 liters of water or
10 grams per 25-liter pump, totaling up to three applications during the cycle.
After applying Azoxystrobin three times, 70% Antracol (Propioneb) can be
sprayed at 400 grams per 200 liters of water or 8 bayer cups per 20-liter pump every
already infected crops, use products containing 12.8% pyraclostrobinand and 25.2%
boscalib (e.g. Bellis) at one gram per liter of water or 80% fosetyl-aluminium (e.g.
Aliette) at one kilogram in 200 liters of water.
The recommendations in this factsheet are relevant to:
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