ground line. Frequently, they are covered by awhite fungal mat in which are embedded numerous small, light-brown bodies about the size ofcabbage seed. The fungus can also attack fruits where they touch the soil. The fungus does not growat temperatures below 68 oF.; it requires abundant moisture for growth. Infection takes place belowthe soil line or close to ground level. Control is obtained by sanitation, crop rotation, and by treatinginfected soil with a soil fungicide prior to planting. Seedling DiseaseCausal Agent(s): (fungal - Rhizoctonia sp., Pythium sp.)Seedlings fail to emerge or small seedlings wilt and die soon after emergence. Surviving plants mayhave infected root systems and watersoaked areas on the stem close to the soil line. As the plantsmature, they become more resistant to damping-off. Avoid excessive moisture in the seedbed, plantseed treated with fungicides and use sterilized media for growing transplants. Tobacco MosaicCausal Agent(s): (viral - TMV)Symptoms are light and dark green mottling of the tomato foliage, and curling and slight malformationof the leaflets. Plants may be somewhat stunted if infected when small, but the plants and fruit are notmuch reduced in size if plants are not infected until they reach the fruiting stage. Several strains of thevirus are known that can cause different symptoms. The virus is highly infectious and readilytransmitted by any means that introduces even a minute amount of sap from infected to healthyplants. The most common means of transmission is by handling contaminated plants. The virus mayalso be present in certain types of tobacco; therefore, smokers may transmit the disease. Controlmeasures are: avoiding handling plants more than necessary, washing hands before handling plants,and protecting healthy plants from infection. Double Streak VirusCausal Agent(s): (viral - viral)Caused by a combination of viruses. Leaves show a light-green mottling, accompanied by thedevelopment ...
