FACTSHEETS FOR FARMERS
www.plantwise.orgCreated in Zambia, September 2016
Baking soda against powdery mildew in okra
Recognize the problem
Powdery mildew is a fungal disease. Plants affected by powdery mildew look
like they have been dusted with flour. The disease first starts off as circular
powdery white spots which can appear on leaves, stems and sometimes fruits.
Later it usually covers the entire upper part of the leaves. It affects the older
leaves first. At the end, the leaves turn yellow and dry out.
Background
Powdery mildew affects a wide variety of crops and takes away a plant’s
nutrients. This causes the plant to become weak and the growth rate becomes
slow.
Baking soda (sodium bicarbonate) is a common powder found in almost all the
super markets. It can be used in organic farming. Baking soda works by
creating a harsh environment for the fungus to survive on the leaf. If
available, use potassium bicarbonate which is more effective than sodium
bicarbonate (baking soda). The spray of water and potassium bicarbonate will
kill and prevent the powdery mildew to some extent. When 6-10 out of 100
okra plants are showing the initial spots of whitish powdery growth on the
leaves, potassium bicarbonate solution may be sprayed. When the problem is
expected to become severe, such sprays may not be efficient enough. When
most leaves are covered with the mildew, all actions, even chemical sprays, are
too late.
Management
• Wear gloves
• Mix 9-10 tablespoons (bottle top lid) of potassium bicarbonate with 16
litres of water in a knapsack sprayer.
• Add 3-4 tablespoon vegetable oil or any available cooking oil. This helps
the spray to stick to the leaves.
• Add 9-10 tablespoons of soft dish washing soap (such as sunlight™)
• Close the sprayer well and shake.
• Spray on both the top and bottom of the leaves using a knapsack
sprayer
• Spray once a week for three weeks and switch to 11-12 tablespoons if
fungus is still growing or spreading.
• Spraying should be done in the morning or evening when the leaves are
still moist
• Do not spray on okra that is soon to be harvested
Scientific name(s) > Podosphaera spp.
The recommendations in this factsheet are relevant to: Democratic Republic of the Congo, Malawi, Tanzania, Zambia
Authors: Jacqueline Mweembe
Ministry of Agriculture
tel: mweembejay@gmail.com email: +260977478715
Edited by Plantwise
Plantwise is a global initiative led by CABI
ZM075En
Lose Less, Feed More
Whitish powdery mildew attack on
okra leaves. (Photo by Scot Nelson)
Baking soda. (Photo by Melissa
Baldwin)