Gardeners’ queries

Press, 5 December 1986, Page 18

Gardeners’ queries

Last year maturing pears and apples were attacked by wasps and virtually ruined. We have been unable to locate any wasps nests, nor

do we know how to cope with them — the usual prophylactic sprays for pests, etc., seem to hold no fears for the wasp. Is there an easy way for searching out the wasp nests or method(s) to deal with them? M.R. (Hokitika).

Wasps are not deterred by the application of insecticides to fruit, and there-appears to be no preparation or method now available which will stop their attacks. Every attempt should be made to discover and destroy their nest, which may be found by following them back to it. The best time to track them back is at dusk, but this may require patience. When found, the entrance to the nest should be dusted with carbaryl, D.D.T., or lindane, applying at least 50g in and around it.

I may be too late to identify the blight from these leaves from an apple and a pear tree. Those of the pear look like fireblight, but do apples get this too? Is there a cure? R.S. (Chch). Fireblight is a bacterial diesease which has a fairly wide host range amongst members of the Rosaceae family, as well as some unrelated species. Although pears are the most susceptible to this disease, apple is not immune to it. However, it has not been possible to ascertain the problem from the samples submitted, because several diseases display somewhat similar symptoms at this early stage. A short length of stem should be included if resubmitting. The inclusion of Bordeaux mixture in the spray programme and the application of streptomycin during the season help to control the incidence of fireblight. Cankers and diseased branches should be cut out, the latter at least 15cm below the last visible sign of infection.

Could you provide the botanical name for what is commonly known as Solomon’s Seal? M.N. (Chch).

The botanical name for Solomon’s Seal is Polygonatum hybridum although it is usually listed and sold as P. multiflorum.

I recently bought Aiew rose which is growing?>well

except that the leaves are blotched on one branch as per sample. As it is a variety which invites aphids, I wonder if there is any connection? A.E. (Chch). While a few aphids were noted on the leaves of this rose, the main concern is the presence of powdery mildew which is showing signs of becoming very prevalent. The combination of acephate and triforine has been found to provide very satisfactory control over both problems as well as some others when applied on a regular basis on roses and can be recommended.

Two years ago I cut back my lemon tree and the hoya in an endeavour to get rid of the black coating which got on the leaves and fruit. With the resulting regrowth so has come back this thick black coating. What is the cause and remedy for this presence? R.B. (Chch). Thorough spraying with summer oil or an all seasons oil, repeated in two to three weeks time should give adequate control of the scale insects responsible for the blackened appearance of the foliage of both plants. These insects exude a sticky substance commonly known as honey dew which attracts a black mould, to develop on it.