Dealing with pests on roses between rain spells

The rains have woken up not only the roses, but the pests as well, especially the big flower eating beetles. Going around the rose farm I see three to five beetles on almost every scented bloom on “Lady of Shalott” and “Molineux” but not a single beetle on “Roald Dahl” which is of a similar yellow gold colouring.

When smelling the blooms even my nose could detect a difference in the scents of the various blooms. After spraying with Rose Protector or Plant Care two weeks ago they disappeared and have not returned. Gardeners who don’t like using pesticides can pick the beetles off the blooms and drop them into a bucket of water to drown. The big yellow and black CMR and fruit beetles are usually active in the middle of the day so are easy to spot.

Less easy to find are the brown “Christmas beetles” that lace the rose leaves. They are active at night and the easiest way to eradicate them is to use a 2-litre hand spray filled with Plant Care, Cyper, Garden Ripcord, Acephate or any insecticide. They usually take the hint and disappear for a while. Thrips remains the biggest spoiler. If new growth is small, deformed and wrinkled and the bud is tiny, then the cause is thrips. It is very hard to get rid of, and we have experienced that even on the rose farm.

In one corner where thrips was particularly resilient we drenched the bushes with Koinor (2ml diluted in 1 litre of water and poured around the rose) followed by spraying the foliage, from top to bottom with the same Koinor mix. Only then did we get clean, new growth. The benefit of using Koinor is that it also controls aphid, boll worm and smaller beetles. The other effect of the rain is that it dissolves the fertiliser that has been in the soil for some time and the roses benefited from it. However, one can see from the new light green foliage that the fertiliser has been used up or has been flushed to deeper levels.

Fragrant ‘Lady of Shalott’ also attracts beetles. Picture: Supplied

I have a bucket of Vigorosa fertiliser on my golf cart and as I drive around the farm, apply it to the bushes that are evidently in need. S u m m e r grooming We usually advise gardeners to trim their roses around middle of January. However, drought-stricken roses that have been brought to life by the rain do not require any grooming or pruning right now. Every leaf helps to strengthen the root system. An application of Vigorosa fertiliser speeds up the new growth and the flowering.

Summer pruning is advised where the growth has become so dense that the leaves take longer to dry off after the rain, which makes them susceptible to black spot. Another reason for cutting back would be to reduce the height of very tall growing varieties to bring the new flowers within reach or simply to improve the quality of the new flowering stems.

This means that there are no uniform rules or instructions for summer pruning or grooming. Rather check out the performance of each bush and proceed accordingly. Other rose care The overcast and rainy weather in Gauteng would be the cause of black spot infection leading to defoliation. Spraying with Ludwig’s Insect Spray mixed with the fungicide Chronos fortnightly would prevent this. Rose Protector is best used monthly or alternated with the cocktail.

In between rain spells, water deeply at least once a week, to provide the equivalent of 15 to 20mm of “rain”, which takes about 45 minutes.

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