Here we go again, another late blight (Phytophthora infestans-Plant Destroyer) warning for tomatoes and potato plants.
Late blight is highly contagious oomycete (water mold) producing millions of spores which travel 30-40 miles a day by wind. Late blight effects even disease resistant plants and unlike early blight, which does not kill the plant, late blight is normally a death sentence for tomato and potato plants.
In 2009, late blight affected tomatoes in the Northeast and Mid-Atlantic regions. In 2012 late blight was reported on tomatoes and potatoes in PA. As of July 2nd, late blight was found in Delaware and in South Jersey. Late blight was responsible for the Irish potato famine of 1845, and the death of over 1 million people, who's diets were dependent on potatoes.
Home growers should check their plants daily and take appropriate action. Protecting plants in advance of disease infestation, seems to be a better approach. Apply a fungicide that targets late blight, making sure the product is safe for tomatoes and potatoes. (Unfortunately, copper, sold as an organic fungicide, has not been successful in preventing late blight.)
There are roughly 19 diseases (fungal, bacterial, and viral) that target tomato plants. Take steps to help reduce the risk of one or more of these infestation. Proper spacing of plants, good air circulation, weed control, and proper watering techniques help reduce diseases in the garden. Water from below with either a garden hose, irrigation system or soaker hose to avoid splashing the leaves (which spreads the spores). If you must water from above, do so before late morning, to give the plants plenty of time to dry off. Mulching around your plants helps reduce the need to water frequently, controls weeds, and reduces splashing of spores from the soil onto the plant itself. For tomatoes, remove suckers plus damaged or weak looking stems. I also remove about the first 8" of stems from all my tomato plants. Tomatoes are actually vines and unless supported, will crawl on the ground, making them more susceptible to disease and insects. Supported plants are easier to prune and treat with garden dust or sprays.
Eventually, infected plants need to be puled and destroyed. Never compost diseased plants (of any kind). Remove the entire plant, place in a black trash bag, and "bake' in the sun to kill spores etc. Burn or throw away in the trash.
Be mindful of airborne diseases and their effect on not only your garden, but your neighbors gardens as well as local agriculture farms.
|pinch at the base using your fingers|
|and remove the sucker|
|removing the first 8"|
More info on Late Blight