Tomato Issues
If tomato plants have blossoms but are not setting fruit, this is likely due to weather. Tomatoes are self-fertile and do not need insect pollination. The most common cause of a lack of fruit is temperature. High temperatures reduce tomato pollination, causing flowers to drop without forming fruit. For tomatoes, day temperatures between 70 to 80 degrees F. and night temperatures between 60 to 70 degrees are ideal. Temperatures below 50 degrees or over 90 can prevent tomato pollination.
In addition to temperature, dry soil can result in fruit drop and high humidity creates sticky pollen that does not transfer well. Excess nitrogen can lead to succulent leaf production at the expense of flowering and fruiting. For tomatoes, use nitrogen fertilizer as recommended and keep soil uniformly moist, not too wet and not too dry. As long as tomato plants are healthy, they will begin to set fruit.
If tomato leaves roll or curl upward, this could be physiological leaf roll. It is not caused by disease, insect or herbicide drift. If tomato leaves roll up lengthwise but otherwise appear normal when the leaf is unrolled, this is physiological. If leaves are distorted, especially the veins, its likely herbicide injury but may be a virus disease.
With leaf roll, tomato plants that grow vigorously during spring, especially due to good rainfall or excess nitrogen fertilizer, can have leafy growth exceeding root growth. When temperatures become hot, and a well-established root system is needed, tomato plants respond by rolling leaves to reduce leaf surface area which decreases loss of moisture via transpiration.
Some tomato varieties of are more prone to leaf roll than others. Physiological leaf roll is a temporary condition. It stops once plants acclimate to hot weather, establish more roots, or have a chance to recover from excessive rainfall or root injury such as from deep hoeing near the plant.
As tomatoes begin to develop fruit, a leathery brown area may appear on the fruit bottom. This is not a fungal disease, but due to a lack of calcium in fruit. In most cases, there is plenty of calcium in the soil but roots are not efficiently taking it up. This can happen if the root system is underdeveloped or soils are too wet or too dry. If excess nitrogen is used, lush leaves may be using calcium before it reaches the fruit. Applying calcium to soil or attempting to spray it on tomato plants or fruit is not needed and does not help. Tomato plants eventually adjust and blossom end rot stops. The most important thing is to maintain a uniformly moist soil and use an organic mulch to help. It is important to avoid excess nitrogen fertilizer to avoid succulent foliage.
A disease recently is tomato early blight. Early symptoms are brown spots on leaves that have concentric rings in them. Leaf spots appear on lower leaves first. If the variety is not early blight resistant, and conditions remain wet from rain or overhead irrigation, this disease can progress fairly quick, moving upward and killing leaves.
Use mulch beneath plants to reduce soil splash, avoid overhead irrigation, and apply a fungicide labeled for use in vegetable gardens according to label. Fungicides will not kill the fungus or cure infections that have occurred; they will prevent new infections to slow the spread of early blight.
Source: Kelly Feehan
