Is this downy mildew on my broccoli?

Broccoli    Charleston, South Carolina USA

hello family,

There is discoloring and senescence of all our broccoli plants. It has rained a fair amount this last week. Any idea what it is and what to do about it?

Posted by: Carmnicole (1 point) Carmnicole
Posted: November 28, 2014


Does it leave a powdery residue on your gloves/fingers?

Posted by: David Hughes (54 points) David Hughes
Posted: November 29, 2014

To diagnose downy mildew, I would suggest turning the leaf over and looking for signs of a grayish white (dusty or powdery) fungal growth. While you have the leaf turned over, look for insect feeding such as a colony of aphids. But honestly, this looks like a mild case of sun scald. If you had a series of rainy days and then some bright sun, you could see some sunburn. The flatter part of the leaf (where it starts to curve downward) is the most exposed to the sun and the most likely place to be affected.

Posted by: Charlie B. (2 points) Charlie B.
Posted: December 5, 2014

This does not look like downy mildew to me. I am in agreement with the above answer regarding sunburn/scald. If leaves were covered up by anything or shaded for a while and then abruptly exposed to harsh sunlight, or there were several dark or rainy days followed by strong sun, there can be some sunburn on the leaves. A similar symptom can be seen from mild frost/cold damage, but due to your location and broccoli's status as a fairly hardy plant, I doubt that is the case here.

My biggest issue with broccoli anymore is clubroot, which manifests as swollen, knotty growths on the roots. Above ground, plants wilt severely on hot or dry days, and their growth slows or ceases. They may also head prematurely.

If the only problem is sunscald/burn, the plants will likely recover and go on to produce well. If there is another problem, they may continue to decline. Be vigilant for additional symptoms, as this can help determine any additional issues.

Posted by: Allison (2 points) Allison
Posted: December 21, 2014

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