It is one of the easier diseases to spot, as its symptoms are quite distinctive. Infected plants display white powdery spots on the leaves and stems. The lower leaves are the most affected, but the mildew can appear on any above-ground part of the plant.
Powdery mildew grows well in environments with high humidity and moderate temperatures.
Natural enemies include predatory ladybirds, hoverfly larvae, parasitic wasps, aphid midge larvae, crab spiders, lacewings andentomopathogenic fungi like Lecanicillium lecanii and the Entomophthorales.
Aphids can be easily killed by unfavourable weather, such as late spring freezes.Excessive heat kills the symbiotic bacteria that some aphids depend on, which makes the aphids infertile.Rain prevents winged aphids from dispersing, and knocks aphids off plants and thus kills them from the impact or by starvation. However, rain cannot be relied on for aphid control.
Plants exhibiting aphid damage can have a variety of symptoms, such as decreased growth rates, mottled leaves, yellowing, stunted growth, curled leaves, browning, wilting, low yields and death. The removal of sap creates a lack of vigour in the plant, and aphid saliva is toxic to plants. Aphids frequently transmit disease-causing organisms like plant viruses to their hosts.
There are various insecticides that can be used to control aphids. There are many plant extracts and plant products that are eco-friendly and control aphids as effectively as chemical insecticides. Shreth et al. suggested use of neem products and lantana products to protect plants against aphids. For small backyard infestations, simply spraying the plants thoroughly with a strong water jet every few days is sufficient protection for roses and other plants.
Fungal disease that produces symptoms such as wilting, premature leaf drop, damping-offThe "F" in hybrid tomato disease resistance
Symptoms simliar to Fusarium wilt.No chemical controlcrop rotation, the use of resistant varieties and deep plowing, may be useful in reducing the spread and impact of the disease.The "V" in hybrid tomato disease resistance
Tomato Mosaic Virus
The first symptom of this virus disease is a light green coloration between the veins of young leaves. This is followed quickly by the development of a "mosaic" or mottled pattern of light and dark green areas in the leaves.The "T" in hybrid tomato disease resistance
The "N" in hybrid tomato disease resistancePlanting of marigolds can control nematodesMicroscopic roundwormsCauses root disfunction
Dry weather that gives way to excessive watering or a rainy period can lead to cracking.
Here’s what happens when a tomato cracks:Tomato plants get too much water too fast. A tomato’s interior grows quickly as it absorbs the extra water from rain or disproportionate watering, but it expands too fast.The tomato skin can’t stretch to accommodate the extra fluid. Cracking alleviates pressure.
How to Prevent:
Plant crack-resistant tomato varieties that have elastic skin
Mulch plants (wait until they’re established – about 3-5 weeks after planting) to help retain moisture in the soil.
Keep water supply even throughout the season.
Apply balanced fertilizer. When blossoms and fruit develop, tomatoes need more phosphorus and potassium. Excessive nitrogen can cause plants to grow too quickly, leading to cracking.
Don’t over-fertilize. Excess nutrients can cause a growth spurt. Tomatoes can have a hard time compensating and may crack.
Beefsteak varieties are more prone to cracking.
If tomato plants dry out, water them just enough to keep them alive. Too much water at one time sets up conditions for tomato cracking. Once your plants have recovered from their dry spell, slowly re-establish a regular watering schedule.