Septoria leaf spot appears as tiny, round gray lesions with black margins on leaf tips. Fungal lesions grow, combine, and cause yellowing and the death of leaves. When the first fruit begins to develop, lesions frequently emerge. The lesions include tiny black pycnidia.
One of the most common tomato foliar diseases is Septoria leaf spot. It may be very destructive under the appropriate circumstances and has been known to cause crop failure. Despite the fact that the causal fungus does not directly infect the fruit, defoliation causes losses, which can lead to fruit failure and sunscald of exposed fruit.
The illness generally appears in early to mid-August, when the foliage has gotten thick enough to limit airflow within the canopy. The humidity remains high when the canopy closes, and any free water on leaf surfaces dries more slowly. When the relative humidity is at 100 percent for more than 48 hours, the infection might develop. These circumstances build up over time and might last for several days. Septoria thrives in temperatures ranging from 68°F to 77°F. The illness typically begins on the lowest leaves, where humidity is strongest and fungal spores are most likely to fall.
Signs and Symptoms
Septoria on tomato leaves appears as 1/16-to-1/4-inch broad water spots. As the spots grow, they develop brown borders and are lighter than cores, transforming them into septoria leaf cankers. The existence of tiny black fruiting bodies in the middle of the dots would be confirmed using a magnifying glass. These fruiting structures will mature and burst, releasing additional fungal spores into the environment. The disease leaves no scars on the stems or fruit, although it does move upward to younger foliage. Tomato plants lose vitality as a result of Septoria leaf blotch or spot. The septoria leaf cankers stress the leaves so badly that they fall off. The disease spreads up the stems, causing all of the leaves it attacks to wither.
Control and prevention
Take out any unhealthy leaves. Lower diseased leaves can be plucked and burnt or destroyed if detected early. Removing leaves above where the fruit has developed, on the other hand, may weaken the plant and expose the fruit to sunscald. Collect all leaves from diseased plants at the end of the season and dispose of or bury it. Diseased plants should not be composted.
Increase the movement of air around the plants. Stake or cage the plants if they can still be handled without damaging them to elevate them off the ground and facilitate rapid drying of the foliage. Mulch around the plants’ bases. Mulching will prevent soil from splashing, which may include fungal spores linked with trash. After the earth has warmed up, apply mulch. Watering should not be done from above. Overhead watering promotes infection and illness transmission. To keep the leaves dry, use a soaker hose at the base of the plant—water first thing in the morning. If the methods do not manage the illness, fungicidal sprays may be used. Fungicides do not heal diseased leaves, but they do keep fresh leaves from being infected.
