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Climatic and environmental accidents

- Thermal stress

Cucurbits are rather temperature sensitive. Field crops of zucchini and squash, and to a lesser extent under shelters, which are subject to climatic hazards sometimes present very damaging pathologies, especially on the fruits.

  • Sunburn on fruits   
The fruits of cucurbits are very delicate organs. Their tender, waterlogged tissues become superficially "dehydrated" when exposed to solar radiation ( sunscald , sun burn ), mainly on their most exposed face. Thus, large irregular patches, whitish to grayish, appear (figure 1). They gradually cork on the surface and cracks and bursts can form as the fruit grows (figure 2).
Almost all the fruits of Cucurbitaceae can be affected, in particular when the foliage which protects them has been more or less destroyed for various reasons: attack by aerial pests, wilting of the foliage linked to a soil pest ... Note that these superficial lesions can be invaded by various secondary saprophytic fungi that cause rots

- Hail

Thunderstorms accompanied by heavy rains, hail can cause lesions on all aerial organs of zucchini and other Cucurbits. In fact, hailstones, by striking the leaves, cause holes and tears which can greatly alter their photosynthetic potential subsequently, some leaves being completely shredded.

Hailstones are also the cause of necrotic changes, more or less pronounced bursts at their point of impact on the stem , petioles and peduncles.

The young fruits of zucchini and squash are very sensitive to hailstones which can cause them indelible lesions which will subsequently make them unmarketable. Corky spots, bursts corresponding to the points of impact of the hailstones will dot the fruit.

In general, the distribution in the crop of affected fruits will be generalized.
- Lack of water

Remember that bad weather conditions can have repercussions on the fertilization of flowers, and lead to fruit sagging .
Last change : 04/19/21
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