Xtremehorticulture

Black Spots on Tomato Leaves May Be Septoria

Q. I have these small black spots developing all over my tomato leaves. Any idea what is wrong with my tomato plant?  Possible Septoria leaf spot disease on new transplants A. From your pictures it looks like you could have a couple of things going on. The tiny black or brown spots on the leaves may be a disease called Septoria leaf spot. As a precaution, I would apply a fungicide for vegetables immediately and follow the label directions to a tee. Any general fungicide for vegetables will work. It usually requires several applications in sequence. Push some new growth with a light application of a tomato fertilizer. Another shot of possible Septoria. Fungicides are primarily meant for disease prevention, not for curing a disease once the plant has it. Applying a fungicide protects new growth as it emerges so new growth should be healthy while the infected growth does not get worse. The other option is to pull it out and start over. Secondly, never apply irrigation water with a sprinkler; use drip irrigation. If you bought these plants from a local store it probably came with the plant when it was grown in the greenhouse and shipped to the store. This disease is fairly easy to control if a greenhouse is kept clean and the plants kept healthy. Such is the problem when buying low-priced transplants. They were most likely infected when you bought them. There were probably some leaves already showing these spots. Your other pictures show leaves of tomato with edges that are scorching. These scorched margins have a yellow inner margin. This is possible salt damage. Reminds me more of salt damage but …… Soak the soil with water. Use a soil wetting agent like EZ Wet or comparable and apply it to the soil to remove salts. Hopefully you amended your soil with compost at the time of planting and you used a pre plant fertilizer. Also some leaves showed signs of yellowing which may be due to lack of fertilizer applied at the time of planting. Once tomatoes start setting fruit it is important to feed them lightly to continue healthy growth. Take a look at these fact sheets and pics. Cornell’s Fact Sheet on Septoria on Tomato Missouri Botanical Garden Fact Sheet on Septoria on Tomato

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How to Get Fewer Disease Problems on Tomatoes

Q. At the nursery I purchased some heirloom tomatoes. They got silvery/shiny areas on back of leaves which turned into dry dead spots.  The plant is also dropping blossoms what is this? I applied fungicide but do not know if this is appropriate. My homegrown tomato plants do not have this. Please let me know.  I do not want my other tomato plants infected. A. You have noticed something that I have been talking about. This is concerning the quality of homegrown vegetable transplants being superior to the transplants grown by commercial growers for the mass markets.             To get transplants ready for markets growers usually have to grow transplants in some sort of protected culture such as greenhouses, cold frames, hot frames or hoophouses. When grown for mass markets the grower has to produce transplants at the lowest cost possible to improve profit margins.             This may mean that in many cases these transplants may not be grown under the cleanest conditions and the growing conditions also may not be the best. This means that mass market transplants can be very subject to earlier development of diseases and insect problems.             When you grow transplants at home you can afford to start with cleaner materials and as a consequence have fewer insects and diseases to contend with. You can also get the exact variety you want by ordering the seed ahead of time.             Sometimes the commercial grower will apply pesticides just before shipping transplants to the nursery to remove any pest problems that might be developing, pests that may already be there and make sure they are pest free when delivered to the nursery.             Several problems can cause silvery discoloration to the leaves including the natural silvery-green color of some tomato plants. These dead spots may or may not be related to the grey green color of the leaves. The brown spots could be due to feeding damage by insects or a disease problem. It is hard to say exactly without seeing a fresh plant sample with the disease present or several high-quality pictures.             As far as blossom drop on tomatoes remember that they are finicky. Temperatures to high during the day, too low at night, and irrigation which is missed, an unusually hot day when temperatures abnormally been cool, all can play a role. Tomatoes grown excluding bees for pollination may cause the flowers to abort.             If you are worried about a lack of bees then use your electric toothbrush to vibrate the plant for better fruit set. Touching the electric vibrating toothbrush to portions of the plants close to the flowers for a few seconds may improve fruit set if bees are limited.             I would suggest you consider applying some preventive sprays to transplants brought into the garden from a nursery or garden center. This is seldom needed for homegrown transplants or from commercial growers who maintain clean facilities and planting material. Sprays would include insecticidal soap applications every few days, spraying Neem oil and some other organic sprays specifically for vegetables.             In the future I would recommend growing your own transplants if you can and you will see fewer problems like you are mentioning. Local producers of vegetable transplants can be found and are usually higher priced but cleaner with fewer pest problems.

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