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Lime-green leaves

Amanda van Wyk of Gordon’s Bay writes My white ‘Iceberg’ and ‘Burgundy Iceberg’ roses are looking so sad! The new emerging leaves are yellow with dark veins, and some even look burnt. We live in a very windy coastal area, but they are not new plants and have survived many a South-Easter over the years. What could be ailing them?

Ludwig replies

The older dark green leaves are evident that the roses were able to absorb water and nutrients after last winter’s winter dormancy and pruning. However, once the roses started blooming, the communication between the leaves and roots changed, with the plant requiring more phosphate and other micro-elements for flowering and formation of seeds (hips).

Once roses have bloomed and been deadheaded, the roots need nitrogen and potash again for growth. If the roots are not able to find or absorb certain micro-elements such as iron, boron and nitrogen, the newly formed leaves will show signs of chlorosis (loss of normal green colouration). It is possible that the roots stretched to a different depth in the soil or into standing water because of all the rain. The soil may also be more alkaline or compacted. Fertilising before the flowers fade could alleviate this but where leaves are already chlorotic, fertilising with ammonium sulphate could help the leaves to turn green again.

It is relatively easy to improve soil texture by adding clay to very sandy soil, sand to clay soil, lime to very acidic soil and acidic fertiliser to alkaline soil, as well as lots of organics such as compost, manure, milled bark and peanut shells to provide the optimum growing conditions.

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