Long periods of drought with concurrent high temperatures are causing a considerable drying out of the soil. The cultivated plants are in this case not provided with enough water in order to provide enough crop yield. When the roots of a plant realise that they are not  having enough water at their disposal,  they are sending an alarm signal – in the form of a stress hormone – to the leaves. This is causing the leaf stomata, those are the small openings in the leaves, to close. Normally, there is water (and oxygen) leaving through these stomata to the outside, while carbon dioxide (CO₂) is absorbed into the leaf. By closing the stomata, the plant is attempting to protect itself from drying out.

This is good, on the one hand, since by doing so the plant can avoid the water loss (of up to 90 percent). On the other hand, the plant cannot perform any photosynthesis during this time, since for doing so the stomata have to open up again and let CO₂ in.

The result is a stagnation in the growth of the plant, which at this point can already result into losses for the farmer. For the time being, this is not affecting the plant too much, since this way the plant can live on and survive for some time. However, if it remains too dry, the plant is not succeeding in closing the stomata. Then the cells are losing water and the plant is wilting. Due to the stress, there is also more sugar being produced, which is in turn attracting insects harvesting it, but consequently injuring the plant and therefore also allowing fungi to establish themselves.

There is a short-time effective solution for this problem and a long-term strategy for addressing future drought as well.