In May the Gunn High School Spanish for Native Speakers class worked hard to plant their bed of Latin Heritage veggies. As mentioned in the last newsletter, the class returned after the summer to enjoy a good harvest of tomatoes, peppers, onions, and cilantro to make a tasty pico de gallo salsa. Tomatillos are related to tomatoes, but have a papery sheath surrounding the fruit, which is green to purple. They make a sweet, tart green salsa verde (my personal favorite salsa). roasting them brings our their sweetness.
The tomatillos that the kids planted started off looking great, but by late summer having produced a lack-luster crop, began to turn yellow-gray, showed holes in their leaves, and this week began to exhibit whitish leaf spots. Check out a comparison of two tomatillo plants in our garden, located in different beds.
What is the problem?
The most obvious problem is a case of powdery mildew, that results in the white spots on the plants leaves. Tomatillos are rarely affected by diseases, and this seams to be a rare case. Powdery mildew can be controlled with sulfur, if applied before the infection takes hold (too late!). UC Integrated Pest Management indicates that the best control for the disease is prevention. We allowed the plant to sprawl on the ground, as we had run out of tomato cages to prop it up. This would have resulted less air flow around the plant and the plant’s surfaces being more moist. Fungus loves a moist plant!
The pale, dry look of the leaves could have been caused by whitefly sucking the sap from them, but the flies themselves and ants they attract are not obviously present. Spider mites are another pest that suck the chlorophyll out of leaves, leaving tiny white spots behind. Wilt diseases can also cause yellowing, dried out leaves. As we mentioned last time, our cherry tomatoes likely contracted vericilium wilt.
This time the problem may be fusarium wilt which causes largo portions of the plant to yellow at once. It often pops up after periods of hot weather (like the last two months!). As a soil born fungal disease, there aren’t terribly effective controls that can be used, save for good crop rotation, so the problem doesn’t build up in the soil.