When relative humidity is greater than 85% and tomato plants are growing rapidly into denser plantings (so air circulation is reduced) leaf mold thrives. As a result, leaf mold (known by the scientific name Passalora fulva and previously known as Fulvia fulva or Cladosporium fulva) is commonly found in high tunnels. The fungus can cause leaves to yellow and reduce overall yield.

To control leaf mold, it is critical to improve airflow and reduce humidity by venting and pruning. Additional recommendations include:

• Removing infected foliage can slow the spread of disease from leaf to leaf and plant to plant.
• Avoid excessive nitrogen fertilization.
• Remove diseased leaves, place them in a plastic bag, and destroy.
• At the end of the crop cycle, remove and destroy all plant residue.
• For the following season, consider using resistant cultivars and certified disease-free seed.

Spray options for greenhouse and high tunnel tomatoes can be found using the New England Vegetable Management Guide.

Be on the lookout for Mexican bean beetles (MBB). Adults and larvae feed primarily on leaves, but when numbers are high, they will also damage bean pods. Feeding damage over 10-20% can cause yield loss. Plants are most sensitive in the pod fill stage. Scout for MBB by searching plants for adults, eggs and larvae, and assessing damage. Prompt destruction of beans in the same or adjacent fields year after year.

Annual releases of the larval parasitoid Pediobius foveolatus, timed to coincide with egg hatch, can help control beetle larvae. Field experiments at Virginia Tech have shown that MBB are less likely to colonize and deposit eggs on beans on metalized and white plastic mulches, compared to bare ground and black plastic. Beans planted on metalized and white plastic mulches also had less foliar damage, less pod damage, and significantly greater yields than beans grown on black plastic and bare ground.

Verticillium wilt is caused by two specials of a soil-borne fungi. It infects eggplants, peppers, cucurbits, and many other crops. A yellowing of lower leaves followed by wilting is the first sign of disease. Lesions have a characteristic V-shaped pattern which is widest at the leaf margin. Symptoms can appear on one side of the plant or on one side of a leaf (a more prevalent symptom in eggplant and tomatoes). When the stems of infected plants are cut lengthwise, the vascular tissue exhibits a brown discoloration.

Verticillium species can persist in the soil for many years in the absence of susceptible plants. Follow a 4-5 year crop rotation with non-solanaceous and non-cucurbit crops to reduce inoculum levels in fields. Include grain crops in the rotation. Control weeds as many weeds are susceptible to Verticillium. Remove and destroy infected plant material after harvest. There are no effective chemical controls. Some resistant or tolerant eggplant varieties exist.