Gardeners’ queries

Press, 31 January 1986, Page 14

Gardeners’ queries

Could you please tell me what has caused the spots on the enclosed rose leaves — some bushes have been almost defoliated. These two tomato leaves are from the same variety. One has very large, soft, pale leaves, and the other plant has small distorted leaves. Basamid was used to treat the ground. “Rose Leaves” (Chch).

A very severe infestation of black spot is responsible for the discoloration of the foliage and the shedding of the rose leaves. All fallen leaves should be carefully raked and destroyed. All the rose bushes should be sprayed with a copper based material, benomyl or trlforine. As this disease can become quite persistent once it has become established, as in this case, regular spraying is most desirable in order to control it.

The tomato plants suggest that residues of basamid remain in the soil. It is absolutely essential when using this sterilant to ensure that the soil has been properly aerated before planting or sowing seed.

Please find enclosed a sample of diseased leaf and fruit from our Blackboy peach tree. Could you identify the bug and advise what can be done about it. V.M. (Southbridge).

The fungal infection, brown rot, is the cause of the shrivelled fruit and the cankered regions, on the stems, some of which were already oozing gum. The warm, moist conditions over recent weeks have been very conducive to the spread of this disease in stone fruit. The onset can be extremely rapid, even after picking. All fruit showing the slightest signs of brown rot should be gathered and either deeply buried or incinerated. Infected shoots should be cut off during pruning and the tree should be regularly sprayed with a fungicide such as benomyl or triforine.

I am growing a grafted Beefstake tomato which appears to have grown well. It has plenty of small tomatoes, but the first ones are marble sized and are beginning to ripen. It seems to me that with this premature ripening they will not grow to normal size. Fertiliser has been applied. A smaller variety was grown in the same place last year with success. Have you any comments please. E.C. (Chch).

This query is open to conjecture as insufficient information has been provided and various factors could be involved.: However, it has been most noticeable that tomato plants have made

prolific growth this season and this can affect fruit size especially varieties which produce big fruit. Under such circumstances mineral fertilisers should be used instead of organic ones. Further, it might pay to increase the soluble salt content of the soil by adding potash. This is best in the form of potassium nitrate, at the rate of 50g per square metre and away from the immediate base of the plant. There is another possi-

billty for the small fruit and that is that the variety is not what It is purported to be. Gardeners’ queries should be sent directly to Mr M. Lusty, 56 Way side Avenue, Christchurch 5. Samples should be separately wrapped in a plastic bag with , air holes. Provide representative, good-sized samples, and your name and address. A nom-de-plume can be used for publication.