The spores do not overwinter on the roots or the stems and leaves. LB spores can over winter on those innocent looking tomatoes. The critical issue here is to have zero tomatoes left on the ground through the winter. The best way to avoid problems of LB is to start your prevention program after the first frost and your plants are dead. If you choose the organic route we advise using alternately the Actinovate one week and the copper fungicide the next week repeating this alternating approach until first frost. Remember these products are only effective if used before the disease appears on the plant and should be reapplied every 5-7 days if wet weather persists. With both of these one can spray up to the day of harvest for tomatoes. Ortho Disease Control and Bonide's Fung-Onil contain the same active ingredient. On the chemical side you have Daconil, a product that has 29.6% chlorothalonil in the concentrate. Your organic choices include Copper Sulfate or Actinovate. If you have found LB on one or more plants and have removed them, you may prevent the spread of the disease if you immediately spray the remaining plants with a fungicide. Remove all infected plants and place in the trash not in the compost pile. If there are spots on just a few leaves, remove them and those around them and watch for a day or two. LB moves quickly so if you see a small lesion and its bigger the next day, that tomato goes into the trash. Look inside the foliage to the stems especially near the soil level. Check your tomato plants twice each week more often if there is wet weather. The weather has to be wet, cool (60 to 80), and humid for LB to thrive and spread. This year in NE the LB hit in June while normal time is late July and August. Monitoring techniques and timing in season Spots the size of a pencil eraser on tomato leaves aren't late blight either-the spots this nasty spider mite critter is hard to spot.

If conditions remain moist, abundant white mold growth will develop on the lesions and secondary soft-rot bacteria may follow, resulting in a slimy, wet rot of the entire fruit.Īll Spots On Tomato Leaves Are Not Always Late Blightįor instance, a very common and mild soil-borne wilt makes the bottom leaves of tomato plants grown in the same area year after year turn yellow this is not late blight. Late blight can also develop on green tomato fruit, resulting in large, firm, brown, leathery-appearing lesions, often concentrated on the sides or upper fruit surfaces. On tomato fruit, late blight causes a firm, dark, greasy looking lesion from which the pathogen spore producing structures emerge under humid conditions. Black lesions appear within 3-7 days of infection of leaves. The first appearance of lesions commonly occurs after periods of wet weather. Under moist conditions, a white fungal growth develops and a soft rot collapses the stem of the tomato plant, which turns black. They begin small and firm, then quickly enlarge. Lesions enlarge rapidly and turn dark brown to purplish-black.īrown spots (lesions) on stems are one of the most visible early symptoms. The circular or irregular leaf lesions are often surrounded by a pale yellowish-green border that merges with healthy tissue. LB starts out on tomato leaves as pale green, water-soaked spots, often beginning at leaf tips or edges. When it shows up you see lesions on leaves and stalks the plant loses its leaves all its leaves. Normally it doesn’t show up until August but this year it started killing thousands of tomato plants in June. Once on board it is soil borne and spread by splashing rain water. LB spores travel through the air (sometimes many miles) and on plants sold at the big boxes. The reason was that we had just the right amount of rain and cool days and nights which is perfect for LB to reproduce. However, 2009 is the year when late blight (LB) went crazy. Late Blight ( Phytophthora infestans ) has been troublesome to tomatoes off and on for many years. SPRAY THE TOMATOES EVERY MONTH STARTING WITH PLANTING. ACTINOVATE PREVENTS LATE BLIGHT FROM HITTING YOUR TOMATOES. Late Blight Is On The Rampage On The Tomatoes

Late blight tomato leaves