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Plantwise Factsheets for Farmers

Buckeye rot on Tomato

Phytophthora parasitica; Phytophthora nicotianae

Recognize the problem

Buckeye rot disease is caused by a fungus. This fungus causes brown, green or grey rot on both ripe and unripe fruits. Affected parts show brown-like rings that alternate inside each other. These rings have watery margins which may in the end cover half of the fruit. Fruit rot leads to poor yields.


The fungus is carried in the seed or seedlings. It is carried over from one season to another on the soil by old crop residues. Fruits on or near the ground are infected most. The disease is favoured by warm wet weather. It is mainly a problem of non-staked plants on poorly drained soils.


Non-chemical control:
  • Plant certified disease free seeds from recognised sources.
  • The disease is reduced by practicing crop rotation.
  • To control the disease stake the tomatoes.
  • Plant on ridges and avoid poorly drained soils especially on the lower parts of a farm.
  • Avoid irrigating frequently when using overhead irrigation as it helps spread the disease. Use furrow irrigation instead.
  • Applying mulch keeps the fruit off the soil, which reduces the chances of the disease getting into the fruit.
Chemical control:
  • Where the disease is prevalent, spray the crops with fungicides at fruit set. These include Mancozeb, Metalaxyl-M and copper oxychloride.

When using a pesticide, always wear protective clothing and follow the instructions on the product label, such as dosage, timing of application, and pre-harvest interval.

The recommendations in this factsheet are relevant to many countries where this pest or problem is present

Authors: This factsheet is based on information written for "The Tomato Farming Handbook", first published by KENGAP Horticulture, 2011.
Kengap Horticulture Ltd, P.O Box 12898-00400 Nairobi, Kenya
tel: +254 722 575544; +254 723 491549 email:;
©CAB International. Published under a CC-BY-SA 4.0 licence.

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