Tomato Blight

Tomato blight is one of the most common garden problems for both home and commercial gardeners. This disease loves warm humid conditions and can spread rapidly and easily completely defoliate an entire crop in only a few weeks. There are a number of things you can do to prevent and control blight on tomatoes and ensure that you have a healthy and bountiful harvest. Tomato blight is caused by a fungus called Alternaria solani, there are many theories as to what causes this fungal infection, some experts points to nutritional deficiencies, and to be sure it has been found that healthy plants that have plenty of nitrogen are less susceptible than plants that are grown in poor soil. Other experts point to a lack of lime in the soil and still others say that the fungus breeds in heavy rain fall, with high humidity and very warm temperatures. Blight first appears on tomato plants as small black or brown circles; they may seem harmless or even unnoticeable at first, and this is a good part of the reason why tomato blight spreads so significantly and causes so much damage. You will first notice the lesions at the bottom of the plant with tiny dark out rings with light centers, as it spreads the spots multiply and the leaves start to turn yellow. Soon the blight will travel up the plant turning leaves yellow as it goes. Tomato blight can destroy your entire tomato crop; it spreads rapidly from leaf to leaf and plant to plant. It can entirely defoliate a plant and expose your tomatoes to sun scald.

There are several steps you can take to prevent and then treat blight on tomatoes. Start with seed that is disease resistant, or healthy disease resistant plants. Early season tomatoes are more susceptible so stick with long season varieties. Leave plenty of room between your plants when you put them in the ground to give the air more room to circulate, and be sure as they grow to trim suckers and low growing branches to leave plenty of room between the dirt and leaves. Be sure that your soil is in good condition and feed your tomatoes regularly, healthy plants are not as susceptible to tomato blight as weaker plants are.

Always water in the morning and keep water off of the leaves of your tomato plant, blight needs water to grow and spread. If you live in an area that is prone to tomato blight you can spray with a fungicide every 7-10 days. Most fungicides are only effective to prevent blight or limit its spread, so you are better off spraying before blight sets in or as soon as you see the very first sign of it. After you have spotted blight you will need to remove all infected leaves to keep the disease from spreading and wash your hands between plants as the spores can travel on your hands from plant to plant. Be sure to dispose of the infected waste as blight can live in the ground for up to three years. Be sure to spray your plants with a fungicide to halt the spread of the tomato blight, you will reapply the spray once a week for best control. Marrone Bio Innovations offers an effective fungal and bacterial disease control called Regalia that is derived from plant sources and is much gentler on the environment than conventional fungicides.