Got Tomato Blight?

Got Blight? You betcha. I’ve been not so much fighting blight since it began partway though the summer as watching it slowly eat my tomato plants.

Several things in addition to the weird cool and alternately soggy and dry weather have helped promote blight this year. The upsurge in interest in heirloom tomatoes, which, as superb as many are, are also mostly not as resistant to a lot of the things, particularly fungi, that hybrids were bred to resist. Researchers surmise that a few big commercial nurseries that produce great quantities of non-resistant heirlooms this year shipped quantities of possibly-infected plants to big box stores, which in turn supplied them to a lot of economy—conscious new home gardeners eager for that old-fashioned taste.

I have not, as has been suggested by Cornel and a number of other research universities, applied ‘cooper products’ to my blighted tomatoes. As experts admit, these products are of limited protection against both infection and further damage. Champ WG and NuCop 50 are ‘organic’ products registered in Massachusetts, which has, along with other soggy northeastern states, had a devilish time this year with blight. (In fact everyone I spoke with on a quick trip up through New York and the Adirondacks howled about their lost tomato crops.). Both products are OMRI-listed. (OMRI is the Organic Materials Review Institute.).

Advice from Cornel sources is as follows:
Removal of a few infected plants may slow the disease, but has not been successful in doing so thus far. If removed, bury the infected plants completely, or bag and put in the trash. Don’t compost them.
Home gardeners need to act quickly to make sure that your plants don’t become a source of spores that could infect commercial farms, as late blight spores are easily dispersed by wind….This organism is not seedborne (however, it is tuberborne in potato), so that tomato plants started from seed locally would be free of the disease, at least for now. Some regional farm and garden centers did distribute infected plants from the same supplier. It is likely that many infected tomato plants have been planted across the entire [northeast] region if they originated from larger wholesale stores.
2. If you want to try to control late blight with fungicides, you need to begin spraying fungicide before you see symptoms – and you need to continue spraying regularly. Use a product that contains chlorothalonil. Even here, these products are only effective if used before the disease appears and should be reapplied every 7-10 days, or 5-7 days in wet weather. Chlorothalonil is a protectant fungicide, with no systemic movement in the plant, so thorough coverage is necessary. For organic farmers and gardeners, the options are very limited, since only copper fungicides can be used, and copper is not very effective on late blight. It is easily washed off by rainfall.

Instead of doing anything chemical to combat blight, I’ve been picking assiduously and canning like mad – quart after quart of gorgeous Super San Marzano plum tomatoes that fill a jar with about seven fruits. I’ve enjoyed the fresh tomatoes I have. But I’ve been careful not to spread the spores. I pick tomatoes and then go inside, shuck clothes and wash before doing anything else either in the garden or elsewhere. For good or ill, that’s been my modus operandi. Save and use what you can, don’t spread it around, and hope that next year, which is bound to be different – the hope and the plague of gardening -- will be blight-free.

A large number of anything concentrated in one place and then shipped all over the place is a recipe for exponentially spreading a problem. (We can apply this to all kinds of things: fast food joints, ennui, fear). I’ve yanked out half of the plants, and dumped them in plastic in the garbage, which was hauled off this morning. The rest are slated for disposal this weekend.

I will continue to plant heirlooms, started from seed in my little greenhouse. I will also continue to mix in some hybrids as I do every year. Diversity is the best protection.