Plant Doctor Archive

Unhappy roses

WHAT is wrong with my well established rose bushes - and is there a cure? A couple of my roses went like this last season. I thought it might be weed spray but none has been anywhere near them. My roses are regularly sprayed with two different rose sprays, alternately.

YOUR photo had me puzzled too, as it does look like herbicide damage. However, I sought advice from rose expert Doug Bone who reports he has seen symptoms like this before. In all cases, the affected roses eventually produced healthy growth as spring progressed.

Experts he's consulted consider the problem to be a nutrient deficiency, not caused by lack of fertiliser in the soil but by leaf growth in early spring occurring faster than root growth, so there's a temporary lack of nutrients in the plant tissues. I think it's likely certain weather conditions could increase the problem, such as a warm spell encouraging bud growth, followed by a cold snap.

Other factors probably play a part too, such as soil type and drainage, and some rose varieties are probably more susceptible to the problem than others. So the general consensus is that your plants should improve as the soil warms up. If not, don't hesitate to let us know.

Reproduced with permission from the former Weekend Gardener magazine. The views expressed here are not necessarily those of the RNZIH.