Naturally Bug-Free (9 page)

Chapter 5: Timing

The ecosystem-level approach to insect control that I explained previously is the best long-term solution to bug problems in the garden. But the technique can feel painfully slow as you wait for your garden to come into balance. What do you do in the meantime?

I like to start with timing my plantings to avoid the worst insect problems. I mentioned in chapter 1 how I use timing to keep cabbageworm problems to a minimum, by planting early in the spring and late in the fall when the butterflies aren't out and about. Below, I'll regale you with two more examples of using planting time to outwit pests.

Squash vine borers

Our first approach to squash-vine-borer control was spraying Bt. Visit the glossary for more information about this and other chemicals mentioned in the text.

Squash vine borers were our archnemesis during our early years on the farm, so much so that I even resorted to spraying Bt on the plants' stems. And I'm glad to say that the Bt
didn't
help. Why am I glad? Because if that seemingly innocuous spray had proven effective, I might not have figured out less intrusive ways to keep vine borers in check.

Variety selection was part of my solution, as I'll explain in the next chapter, but the biggest reason I started being able to harvest summer squash is because I learned to succession plant these speedy vegetables biweekly in the summer garden. Here in zone 6 (last frost: May 15, first frost: October 10), I plant crookneck (summer) squash on May 1 (a gamble), May 15, June 1, June 15, and July 1 (a slight gamble), a schedule that allows us to be overwhelmed with tasty squashes despite heavy vine-borer pressure and with the use of no other control measures beyond variety selection.

Yes, the vine borers move in and kill the squash plants eventually, but not until after I've collected at least one big harvest from each bed. By the time the earliest vines start ailing, I have another planting of summer squash just waiting to take their place. Those of you living further north can simplify this campaign further since your vine borers generally only go through one generation per year instead of two, so if you wait out the borers, your late plantings of squash should be pristine.

Succession planting is handy with other types of vegetables as well, although the strategy only works if you choose varieties that put out a big harvest right away. For example, I succession plant bush beans rather than growing runner beans since the former provide lots of green beans before the bean beetles move in to dine. On the other hand, succession planting wouldn't be a good choice for tomatoes since even determinate varieties require months of growth before they ripen their first fruit.

Another benefit of succession planting comes when the food reaches our table. A few studies have suggested that cucurbits (and perhaps other vegetables) have more micronutrients on hand when they mature their first fruits, so the earliest harvest often tastes best. Some gourmet farmers pull out their squash vines after the first harvest as a matter of course, figuring it's better to maximize flavor rather than yield. So maybe the borers are trying to do me a favor by prompting me to eat the most nutrient-rich and tasty vegetables possible?

Cicadas

Periodic cicadas can wreak havoc on new plantings of fruit trees.

I learned my next lesson on timing the hard way. In 2012, periodic cicadas crawled out of the ground and regaled us with their ocean-like symphony. I was intrigued by the natural occurrence and enjoyed feeding these protein-rich insects to our chickens, so at first I thought the periodic cicadas were a boon to our farm. Then I saw this:

Female cicadas lay their eggs on the twigs of young fruit trees, creating extensive scars.

It turns out that cicadas lay their eggs in tender twigs of young trees, and seem to preferentially choose fruiting species over wild saplings. When the young cicadas hatch from their twig homes, the nymphs drop to the ground and tunnel down to feed on the tree's roots. While the root sucking may be a long-term problem, the real issue is that the nymphs damage fruit-tree twigs so much while coming out of their eggs that the branches often break off and die.

Brian Cooper shared these photos of cicada killer wasps "taking cicadas right out of the air."

Of course, even cicadas have natural predators, but the insects' periodic nature is designed to keep predation to a minimum. Cicada killers and other animals that preferentially feed on cicadas can only survive at low population levels most of the time since their food is scarce. Every 13 to 17 years, the periodic cicadas come out of the ground and provide a feast, but by then, the predator levels are so low that the majority of the cicadas survive untouched. That's why we have to get a bit more wily when dealing with these insects—periodic cicadas have outwitted their natural enemies and we can't count on help from nature.

The short-term solution to cicada damage is to net adult cicadas away from the twigs as soon as you hear periodic cicadas calling. But smarter orchardists also plan around cicada cycles. If you go to http://hydrodictyon.eeb.uconn.edu/projects/cicada/databases/magicicada/magi_search.php, you can choose your state and county and then find out when periodic cicadas have emerged in your region recently. Add the appropriate number of years to those emergence dates and you'll know when the next brood will be out looking for baby fruit trees.

In a perfect world, you'd plant fruit trees no more than two years before cicada-emergence dates since cicadas aren't as interested in older trees. Orchardists also choose not to winter prune fruit trees during a year when periodic cicadas are due to emerge, knowing the cicadas will do some of their pruning for them. That's true permaculture gardening at work!

In addition to timing, variety selection can go a long way toward reducing insect pressure in the garden. In fact, choosing resistant fruit and vegetable varieties is my favorite low-work method of insect control in our own garden.

Resistant varieties

Japanese beetles prefer French hybrid grapes over American grapes.

Japanese beetles taught me my first lesson about variety selection. We had a terrible problem with these invasive beetles on our grapevines until I realized that French hybrid varieties are much more tasty to Japanese beetles than are American varieties. The latter can be distinguished by their thicker leaves, which are often whitened underneath, and by the relative paucity of beetles chowing down on the leaves. In addition to grapes, Japanese beetles also defoliated our young sweet-cherry tree, but damage on other plants seemed to stay at low enough levels that the trees could shrug it off. After switching our small vineyard over to American grapes and removing our cherry tree, the Japanese beetle pressure was reduced to the point where hand-picking was sufficient to keep beetles at bay.

In general, variety selection can be a helpful strategy in controlling at least five of the dirty-dozen worst garden pests in the U.S. The table below includes pest-resistant varieties drawn from several different extension-service websites and other sources.

Insect-resistant vegetable varieties