Plant Injury and Gray Mold

Pruning injury of tomato resulting in necrosis and early gray mold infection.

Figure 1: Pruning injury of tomato resulting in necrosis and early gray mold infection.

Botrytis gray mold infection has started on injured tomato stem.

Figure 2: Botrytis gray mold infection has started on injured tomato stem.

We recently published an article in the Hotline about gray mold of tomato.  That article and more details about this disease can be found here. In this short note, we want to share examples of the relationship of gray mold and tomato plant injury.

In the figure 1 above, a pruning injury of tomato in a commercial greenhouse has become necrotic and a gray mold infection is starting.

Figure 2 is from our research high tunnel.  In the photo, one can see where there was an abrasion, probably due to tying the plant in the greenhouse. This injury allowed the gray mold fungus to begin to grow.  Not only will this infection cause a die-back, but the spores produced may cause the disease to spread.  We clipped off this branch to stop the spread of the disease. The photo is taken outside of the greenhouse for better lighting.

The lesson here is that one should avoid injury to plants where possible.  Scout the greenhouse for dead and dying foliage where gray mold may start.  Remove such debris far away from tomato production areas.  If at all possible, prune or sucker plants when the growth is small, therefore reducing injury.

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