Growing zucchini problems - Knowledgebase Question

Franklin, Te
Question by megirwincre
March 23, 2010
I have a problem growing zucchini and squash. Right at the stem close to the ground it decomposes... how do I treat soil organically and not have this problem? This is 2nd yr this has happened and it seems worse. Thanks, Meg

Answer from NGA
March 23, 2010


I can't tell from your description if the problem is with the vines themselves or with the fruit rotting. So, here's information on both problems, which are common to squash:

Squash Vine Borers: These are usually more of a problem with winter squash, but they can be a pest of all squash plants. They look like white caterpillars and they tunnel into stems, leaving yellow, sawdustlike droppings. Keep an eye out for the adult borer, an orange and black wasplike moth that lays eggs at the base of the stem in April or May. Begin checking your plants in late spring for very tiny red and orange eggs on the stems of plants. Rub out any you see. Later in the season carefully check the stems of your squash plant for the droppings. If leaves begin to wilt, or if you see the droppings, the stems have probably been invaded by the larvae. You can carefully slit the stem to remove the caterpillars and then bury the slit part in soil so it can take root. To avoid problems with your squash next season, be sure to plant them in a different area of the garden so overwintering adults or eggs won't have a chance to get to your crop. It is really important to clean up, remove and destroy all of the vines and plant debris each fall to help prevent an infestation next year.

Blossom End Rot:
Squash can be affected by blossom end rot, where the blossom end of the squash turns black and rots. The cause is lack of calcium in the soil and more commonly uneven soil moisture levels. Incorrect watering can also lead to root damage and can encourage mildew infections -- powdery material causes a white substance on the leaves and can cause defoliation much as you described. Watering correctly should stop the blossom end rot and could help with the mildew, and if root rot was due to overwatering would also help with that. (Over watering and under watering can both cause drooping or wilting due to root damage.) Your goal in watering is to keep the soil evenly moist like a wrung out sponge, not sopping wet and not dried out. There is no set schedule for watering, it depends on your soil type and on the weather. To know if you need to water, dig into the soil with your finger. If it is still damp, do not water yet. When you do water, apply it to the soil surface and water thoroughly and slowly so it soaks down to the deeper roots. After watering, wait a few hours and then dig down to see how far the water soaked in; it can be surprising. Using an organic mulch several inches thick over the root area will help reduce watering needs as well as feed the soil gradually as it breaks down over time. You may also want to check the soil pH. If the soil is too acidic, lime would be used to raise the pH; lime would also help supplement the calcium in the soil.

Best wishes with your squash!

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