Winter time is the off season for the gardener. I spend many idle hours leafing through seed catalogs, browsing for new releases of old heirloom seed stock and the latest disease resistant cultivars. At work I steal away to update my rows I have mapped out in AutoCAD to ensure proper crop rotation. Is this overly obsessive, I wonder? No, a successful gardener at rest in the winter is ever thinking about the next growing season. For I have learned that the enemies of my garden, too, lie in waiting for the thaw.

In my garden I like to grow cantaloupes, zucchini, yellow summer squash, watermelons, cucumbers and butternut squash, among other things. Non-gardeners should be aware that all of these plants belong to the Cucurbitaceaefamily, or simply, Cucurbits {1}. Most Cucurbits are very prolific and easy to grow but, like any plant, are susceptible to pests and disease if proper soil management is not practiced.

Several years back I had planted all of my usual favorite Cucurbits. All had grown large and healthy. The summer squash, cucumbers and zucchini were setting fruit. Melons had begun to flower. I had mulched around the plants as ascribed in many gardening books to retain soil moisture and to control weeds {2}.

At some point I took note that some of the older leaves on the zucchini plants were wilty looking. In the following days this worsened. When watering failed to revive the plants I inspected them closer and discovered, hiding on the undersides of the leaves, many grey finger nail sized beetles with sucking mouth parts. I consulted The Organic Gardener's Handbook of Natural Insect and Disease Controland concluded that I had Squash Bugs in my garden: Anasa Tristis {3}.

The Squash Bug feeds by sucking the juices from tissues of Cucurbit plants. The pests overwinter under garden waste, such as mulch, and become active when the host plant has reached a mature size the following year. The female Squash Bugs lay clusters of dark eggs on the underside of the leaves. Shortly, immature Squash Bugs hatch, appearing as green miniature versions of the adults, and begin to feed. The saliva of the Squash Bug is toxic to the plant and is also vector of the Cucurbit Yellow Vine Disease (CYVD). As implied, this causes the host plant to turn yellow, wither and die {4}.

The bacteria reside and multiply in, and eventually clog the phloem tissue of the plant vascular system. Usually symptoms are not detected until just prior to harvest. However immature plants may collapse suddenly in the middle of the season or just after fruit set. Typically, all the leaves turn yellow within a few days, starting about a week or two before harvest. Terminal leaves stand erect, fail to expand, and the margins curl inwards. Older leaves develop scorched margins and may die. The phloem in the crown and lower stem turns honey-colored. Eventually, the root begins to decompose, a process that is hastened by secondary rot organisms, and the whole plant begins to decline and die. {5}

The previous growing season, adult Squash Bugs attracted to all the Cucurbits that I grew, had set up camp under the mulch in the fall. The following summer my garden was infested with their young. Insecticidal treatment of the plants themselves was not effective as the Squash Bugs linger on the underside of leaves only to feed and to lay eggs, retiring into the mulch at night. Over the summer, every cucurbit in the garden had withered and rotted away into yellowish pulp. On the pain of loss of over half of my garden I learned a cardinal lesson of gardening warfare. Never afford the enemy safe haven.

After confirming that CYVD does not persist in the soil, I roto-tilled the dead plants and all of the mulch into the soil and vowed never again to mulch my vegetable garden. When afflicted with persistent drought or heat, I would water vigilantly. I would combat weeds from taking root with the frequent application of the horseshoe hoe and bow rake. But mulch? Never again! Mulch is for suckers!

Postscript: The symptoms CYVD are very similar to another bacterial infection, called Bacterial Wilt, or Erwinia tracheiphila, which are transmitted by cucumber beetles which also are very fond of feeding on cucurbits.

{2} "Better Homes and Gardens New Complete Guide to Gardening", Meredith Publishing.
{3} "The Organic Gardener's Handbook of Natural Insect and Disease Control", Rodale Press.
This writeup was originaly titled Meus nixor per Anasa Tristis but mauler gets the credit for its current, more practical, title.

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