Extension News

Ask the ISU Extension Garden Experts: Vegetables, Acorns, Water Lilies

Note to media editors: Got gardening questions? Call the Hortline at (515) 294-3108, Monday-Friday from 10 a.m. to noon and 1 to 4:30 p.m., or send an e-mail  to hortline@iastate.edu. For more gardening information, visit Yard and Garden Online, http://www.yardandgarden.extension.iastate.edu

10/29/2009

How can I minimize plant disease problems in my vegetable garden next year?

Several steps can be taken to minimize disease problems in your garden next year. An important task is to clean up the garden in fall. Carefully remove and destroy the infected plant debris. Many of the fungi and bacteria that cause plant diseases survive over the winter in the dead leaves, stems, and other plant parts that are left behind in the garden. The fungal spores and bacteria that survive in the garden then attack the new vegetable plants next spring.

Also, annually rotate the placement of vegetables in the garden. Disease problems often increase when the same crop is planted in the same area in successive years. For crop rotation to be effective, gardeners should not plant vegetables belonging to the same plant family in the same location for three years. Selecting vegetable varieties that are resistant to specific diseases can also be helpful.

Many of the acorns on the ground beneath my oak tree have small, round holes in them. What made the holes?

Acorn weevil larvae are probably responsible for the small, round holes in the acorns. The adult acorn weevil is a brown colored beetle with a long, thin snout. It is approximately 3/8 inch long.

Female adult weevils make small holes in the developing acorns and lay several eggs within the holes. The eggs hatch into creamy white, grub-like larvae that feed inside the acorns until fall. In fall, the acorns drop to the ground and the fully grown larvae chew round, 1/8 inch holes in the sides of the acorns. The larvae emerge from the holes and tunnel into the soil to complete their development. They remain in the soil for 1 to 2 years before emerging as new adult weevils to repeat the process.

I have a water garden. How do I overwinter tropical water lilies?

Tropical water lilies are difficult to overwinter in cold climates. Many gardeners treat tropical water lilies as annuals and discard them in the fall.

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Contacts :

Richard Jauron, Horticulture, (515) 294-1871, rjauron@iastate.edu

Del Marks, Extension Communications and External Relations, (515) 294-9807, delmarks@iastate.edu