Aaron Griffing, Pinnell-Alison, Carol L.
Blossom end rot
Leaf footed bugs
Glyphosate (Roundup) injury
Tomatoes are a favorite vegetable in a home garden. It is very common to get visits or calls from distressed gardeners with tomato plants or fruit that have something wrong with them. Cloudy and rainy days late winter and early spring are the perfect conditions for problems with growing plants of any kind. A common concern is having a large healthy plant but no fruit. This is usually due to over fertilizing the plant especially with nitrogen. The over fertilization keeps the plant in its growth stage and delays the plant from converting to its reproductive stage of flowering and setting fruit. Once the plant begins to fruit, the first cluster of fruit may have blossom end rot. This is a physiological disorder caused by the plant roots not being able to take up enough calcium. Calcium is not a highly mobile element in the soil. Factors limiting root growth like cold wet soils or a fluctuation in water supply can cause the condition. Other factors are rapidly growing plants due to over fertilization with ammonium nitrogen, insufficient calcium in the soil and high relative humidity. Taking a soil sample for analysis is an inexpensive way to check on the fertility needs of your garden site. The LSU AgCenter has a soil testing lab on main campus in Baton Rouge. The cost to analyze a soil sample is $10.
As the plant grows there are many diseases and insects that can damage the plant and fruit. It is important to select tomato varieties that have resistance to diseases for planting. Fungicides can be applied to control fungal diseases but there are no pesticides that will control virus diseases like the tomato spotted wilt virus. Common insect problems are stink bugs, leaf footed bugs and tomato hornworms. It seems that tomato hornworms can defoliate a plant overnight. Insecticides can be used to control insects. Make sure to identify the disease or insect correctly and apply the correct pesticide for their control. Read and follow the pesticide label for all mixing, application timings and fruit harvest intervals after an application.
As the weather gets hotter our spring planted tomato plants begin to produce less fruit. High nighttime temperatures reduce the viability of the pollen. It is best to plant a second crop of heat tolerant tomato plants if you want to continue harvesting fruit through the summer and fall. Some heat tolerant varieties are Bella Rosa, Tribeca, Tribute, Floralina, Florida 91, Heatwave II, Solar Fire, Solar set, Sunmaster and Phoenix.The LSU AgCenter has several publications available for gardeners. Some of these are free and can be picked up at your local Cooperative Extension office.We have several publications for purchase which may be ordered from our web site through our online store.
One frequent question concerning a tomato plant disorder is related to weed control. Tomato plants are very sensitive to glyphosate herbicide. Many home gardeners unintentionally spray glyphosate too close to their garden resulting in a yellowing discoloration in the leaves. Home gardeners have a limited number of herbicides available for weed control. Herbicides are either broad spectrum in their control of weeds (an example is glyphosate) or they control either broadleaf, grass or sedge weeds. Glyphosate is usually applied to kill all emerged weeds in a garden area in preparation of preparing a site for planting. There are pre-plant incorporated herbicides like trifluralin, pre-emergence herbicides like metolachlor and DCPA and post-emergence herbicides like bentazon, fluazifop and sethoxydim. Follow the pesticide label to make sure the product may be applied to the vegetables you are planting. Fluazifop and sethoxydim are both products that will control grass weeds. You would not apply them to your sweet corn that is also a grass plant.