Tomato Plant Leaves Turning Black?

Question:

In my greenhouse last year my tomatoes leaves went black and crispy. Now I have noticed the same is beginning to happen again. How can I stop this before I lose my plants? Would I need to disinfect the greenhouse?

A Northwood

Answer:

A Northwood,

I've included some links below to some websites that may help you identify exactly what is going on with your tomatoes. From what you have described, it sounds to me like you have some type of blight problem going on. If that is the case, disinfecting your greenhouse is going to be essential to preventing further spread.

• Repair tears in screens and seal cracks around doors and windows where airborne pathogens can enter.

• Mulch walkways near your greenhouse to reduce weeds and help prevent the spread of soil-borne pathogens.

• Always make sure all discarded fruit and dead plant debris is removed from your greenhouse promptly.

• Sanitize hands, tools, pots, floors, shelves, etc., on a regular basis.

• Wash greenhouse clothing and shoes regularly in hot water.

• Keep houseplants out of the greenhouse during tomato production.

• Tobacco users should be extra careful to sanitize their hands before touching tomatoes to avoid introducing tobacco mosaic virus to plants.
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• Good ventilation and proper temperature control are critical for reducing humidity and controlling airborne fungal diseases. To ensure good ventilation, allow several feet of airspace above the plants and use proper spacing between them.

• Prune the suckers just below the first fruit set to maintain good air circulation within the plant's canopy.

Links to help with diagnosing tomato diseases:

• http://www.extension.iastate.edu/Publications/PM1266.pdf

• http://aggie-horticulture.tamu.edu/tomatoproblemsolver/leaves/index.html

Good luck!
Ellen