Growing Concerns 590: Environmental Changes, Long Term Trouble


Look for changes in environment before blaming neighbor for garden's failure


Dear Janet,

For 20 years I had a gorgeous vegetable garden. Then a neighbor who had never gardened before, whose garden backed up to mine, put in her first garden and I noticed that all my cucumber plants leaves turned brown and shriveled. I lost all my cucumbers. She told me she had cucumber blight whatever that is.

I now also get it on my zucchini and this year it attacked my tomato plants as well. Everything turns brown and dies off.

It tried Neem but it was not successful. I don't know what is safe to use and still eat the vegetables, or how long after using Neem you must wait before consuming the vegetables. Also, should I spray the soil this fall with a fungicide? Should I wait until spring?


Dear S.M.,

Your neighbor may have planted a mildew-prone type of cucumber and those spores may have taken hold on your plants. Yet it's more likely that neighbor's first try at a garden came during a year and on a site conducive to disease.

Without thorough clean-up the previous year or correction of site conditions that make mildew more likely, cucumbers and close relatives such as zucchini might have the same problem the next year. The tomato, about as far removed from cucumber and zucchini as walrus from parakeet, doesn't share that disease but can fall prey to its own diseases if a site is prone to fungus.

You may say, "Not my garden. It was fine until that neighbor introduced disease!" But wait. Take an objective look at your yard and neighborhood now versus 20 years ago. Have nearby trees and shrubs grown, filled in? Are there fewer hours of light each day, and is air movement less free? Are two sprinklers running there, making it more damp, or at different times so the plants are damp for more hours per day? All these conditions can creep up on a gardener, so we don't notice them until they hold sway and our older garden begins to favor fungus development. Since fungi of various kinds are responsible for most plant diseases, the garden begins to decline.

Clean up and dispose of all infected plants this fall. Prune to admit more light or air, or relocate the garden. Forget trying to treat the soil with a fungicide, which is impractical and inadvisable for reasons we can discuss later if you write again.

Choose the varieties of vegetable you grow for disease resistance, and rotate to crops in different families. Explain your strategies to your neighbor, a new gardener who can benefit from your experience and may agree to coordinate for wiser watering. These cultural changes are far more effective in controlling fungus than preventive fungicides. So you may be able to dispense with the worry about interval between spraying and harvesting (listed on the label of any pesticide approved for use on edible crops).

Short reports

Recent needle-fall on white pines is normal.

You may not notice until you have your own new tree, that white pines drop their two- or three-year old needles every fall, all at once. It can be alarming to see an evergreen develop so much yellow, yet this is normal. Take a look and you should see it is only the older needles that are falling, not those at the tip of each twig.

It can be especially worrisome for a year or two on a white pine that was quite large when it was planted. Such a tree rarely grows as well right away in its new site as it did in the nursery, which means it adds fewer needles each year than it once did.

Let's say each twig was adding 50 needles per year in the nursery but as a new transplant that rate falls to 25 per year. In the first and second fall on-site, each twig will not lose just 33- to 50 per cent of its needles but 40 or 80 per cent of the green.

Baby every new transplant until its new growth rate equals or exceeds the pre-transplant rate. That means checking the soil moisture in and around the root ball, watering regularly, and watching for problems, then interceding if they occur. It's the opposite of what you would expect but smaller plants, not large ones, are quickest to get their feet under them.

Enjoy the smells of fall.

Somehow fragrance is richer when you don't expect it. To the mellow warm tannins of fallen leaves and the tang of cooling soil, add the mellow tone of vanilla from dried Joe Pye flowers.


Green thumbs up

to maintaining momentum in fall. Planned to work outdoors today but it's raining? Stay out. Sharpen your tools or clean the garage. (Perhaps you'll find the gloves or pruners that disappeared this year!) If you go in and sit down you may stay down all winter.


Green thumbs down

to taking advantage of a local garden center's expertise without repaying it with your patronage. Shame on you for having them draw you a free landscape design on the pretense of future purchase, then buying everything at a "big box" store. You proved you value what only local specialists can provide, and will doubtless rely on it again when you run into your first growing problem. You'd better support that or it will disappear.


Originally published 10/30/04