Peter Davies and Mark Scherzer are the owners of Turkana Farms in Germantown, NY. This week Peter writes: While the livestock side of the farm is burgeoning (3 piglets, 2 calves, and our 18th lamb so far this season, as well as 125 turkey poults and 40 goslings arriving next week), it is now the garden side of the farm that is coming very much to the fore. Last week we planted seven flats of heirloom tomatoes, including Brandywine, Black Krim, Amish paste, Principe Borghese, and German striped, in our greenhouse, as well as about six varieties of peppers and a couple of eggplants. To make room, we moved out to the garden our fava beans, peas, lettuces, cauliflower, broccoli, and lettuces, heavily mulching the plants to shield them from cold winds and frosts. Usually it is with great enthusiasm and anticipation that we start our tomato plants, but, given last year’s tomato disaster, it is instead with a sense of trepidation. Up until recently tomatoes had seemed to be a fail safe crop. I have been growing them since I was eight, and I cannot recall a single season until last year in which there was not a very good return on the tomatoes. But, now, apparently, delicious summer tomatoes are something we can no longer take for granted. Fortunately, we do not have the extremely wet, overcast conditions that facilitated the emergence and spread of Phytophthora infestans, the fungus-like pathogen that causes late blight in tomatoes and potatoes. Apparently our weather conditions last year mimicked the climate of Ireland, where late blight decimated the potato harvests in the 1840’s, creating the Great Famine and precipitating the Irish Diaspora. This spring, fortunately, our weather conditions are, so far, on the dry, sunny side. But this, apparently, does not mean that we are entirely safe. In fact, we just came very close to doing something that could have re-infected our garden with the deadly spores. And this is after we thought we had taken all the necessary precautions. At the end of the last growing season, we carefully gathered up all of the tomato plants and spoiled tomatoes and fed them to the pigs. Since then we have learned that the spores cannot survive in dead plant materials, or in seeds, but only in a living host.
Which brings me to our close call. A month or so ago, I noticed that the remainder of our potatoes from last year, even though stored in the cool darkness of our basement pantry, had begun to sprout. Perfect, I thought, we can use these as seed potatoes. I was unaware that, in the Northeast, infected potato tubers are usually the main source (the living host) of the pathogen. We were lucky to have a long list of higher priorities that had to be accomplished around the farm before we had time to dig the potato bed. The delay saved us from introducing a veritable Typhoid Mary into our garden. What finally saved us was that, puzzled because I was not seeing anything in print or hearing any discussion about the likelihood of tomato blight this season, I finally googled “tomato disease” and came up not only with late blight information relevant to 2009 but also updates on 2010, much of the information coming from Professor Meg McGrath, plant pathologist at Cornell University Agriculture Department. Now, instead of using our sprouting potatoes as seed potatoes, we are following Professor McGrath’s advice and sealing them up in a plastic bag, setting it in the sun for a few days to kill the spores, and then safely disposing of the contents (by maybe boiling them up for the pigs). We also, as instructed, will do the same with any “volunteer” potatoes we find still in the ground or sprouting in the garden. While doing this removes the immediate threat, there is still the possibility of infection by way of air-borne spores coming from other people’s gardens or commercial nurseries, which is why it is important that we all destroy all potential sources of the blight. While the above advice deals with destroying the remains of the pathogen from last year, there are also preventative measures Professor McGrath suggests for handling our tomatoes this year. For one, there are varieties available (and some hybrids being developed) that are blight resistant. A source for such seeds is Territorial Seeds. Our dilemma is that we usually grow only heirloom varieties, many of which fell into abeyance precisely because they were not as disease resistant as newer hybrids. None of the tomato varieties we have planted this year fall into the “excellent” or “good” categories of blight resistance; only Black Krim and Brandywine fall into the category of “moderate” resistance (neither variety survived last year). Our concern is that in shifting to blight-resistant varieties, we would be giving up the quality and flavor of the heirlooms and backing off from our farm’s stated aim of helping to save excellent varieties of vegetable plants from extinction. One alternative we are considering is to add a blight resistant variety to our tomato patch as a back up, should the blight return and wipe out our heirloom varieties.
Following are McGrath’s guidelines for preventing or controlling the blight: 1. Keep the tomato plants dry (drip method irrigation as opposed to overhead sprinkling) 2. Be vigilant; inspect once a week, looking for dark brown lesions on stems and for leaves with white fungal-like growth. Remove infected vegetation immediately and dispose of it properly (see #5) 3. Act quickly. If removing foliage doesn’t work, safely dispose of the entire plant 4. Immediately inform near neighbors and the Cornell Cooperative Extension if you have an outbreak 5. Dispose of plants properly. Ideally, remove plants on a sunny day, after the leaves have dried. If you do not have these conditions, don’t delay. Seal plants in a plastic bag and leave in sun for a few days, then bury plants deeply or put them in the trash. 6. Keep an eye on related strains of plants: petunias, tomatillos, and certain weeds, such as hairy nightshade and bittersweet nightshade. 7. Use fungicides (Chlorothalonil and copper-based products) and spray preventatively. We plan to follow these guidelines this summer (with the possible exception of spraying preventatively with fungicides, something we do not ordinarily do). And we are hoping this summer to have delicious tomato plates drizzled with olive oil and garnished with slices of mozzarella and parsley, tasty tomato sandwiches, even tastier bacon, lettuce, and tomato sandwiches, refreshing gazpacho, heaping tomato salads, and soothing tomato soup. And we are hoping to freeze at least 60 pounds of tomato sauce, as we usually do, to see us through those tomato-less winter months. —Peter Davies
