By James1793
Northumberland,
United Kingdom 
Some of the plants in the greenhouse are shrivelling up and have this on their leaves. What does it mean?
8 Jun, 2014
Answers
the white 'powdery'cover is the minerals in the water as it has evaporated off in the heat. the dead bit is due to the heat killing that edge of the leaf. the plant will be ok.
9 Jun, 2014
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It looks like water splashes on the leaves and the shrivelling might be underwatering or look out for webs which could be spider mite, they love greenhouses and the heat.
8 Jun, 2014