Gardeners’ queries

Press, 31 May 1985, Page 15

Gardeners’ queries

I have a Meyer lemon tree, planted last year. Could you advise me about regular spraying to eliminate especially caterpillars, and the black smutty infestation. Secondly, how many times each year sbould such a tree be fed with fertiliser, and should these applications always include cpsom salts. Also, I have a number of Chamaecyparisus — what should be used to keep them free of disease, and when is the best time of the year to make applications? Could you also tell me what is the matter with the enclosed shrub, and how to cure it? — P.R. (Christchurch). A regular spray schedule is not considered essential for lemons, providing periodic inspection is made to check on any developing problems. The smutty appearance of the plant is due to the presence of scale insects, control for which is all seasons or summer oil. It is important to make a thorough and penetrating coverage to control this pest, and the best times are late autumn and spring. It may be necessary to repeat these applications within three weeks. Acephate will deal with most other insects, but should not be applied when the plants are in full bloom. This material can be applied to ornamentals, including the Choisya ternata which is suffering depredations

from leaf roller caterpillar. Lemon trees are usually fed twice a year, at the rate of 450 g for each year of the tree's age to a maximum of 3.5 kg. The application rate is divided with two-thirds initially in August and the balance in December. Epsom salts is applied as a remedy for magnesium deficiency when it occurs, and is not included in the appropriate regular feeding. I have two seedling casitnroas about three years old, one of which is now about two metres high. My problem is that I cannot allow the big plant to get any higher, and that I cannot get any information about them. Any help in this direction, and whether the top could be pinched out, would be appreciated. — R D. (Christchurch). This subtropical plant, commonly known as sapote, requires the removal of the terminal bud when about one metre high in order to promote branching. Failure to do this will lead to a tree which may exceed three metres before producing any lateral growth. Once these laterals have attained about half a metre in length they. too. should be pinched back. It will take at least seven to eight years for seedlings to begin to bear fruit, and it is possible to be of inferior quality. No great

expectations should be placed on productivity under local climatic conditions, certainly not in the open, but it could make a nice glass house or indoor plant. Regarding the recent answer to the query on the possibility of the die-back on roses being the bacterium “blast.” is it likely that a still-to-be-planted weeping standard rose could become similarly affected? — L.V. (Amberley). The main thing in controlling the incidence of this disease is to maintain a high standard of hygiene and ensure that all pruning is done with sharp secateurs properly applied, making clean cuts without leaving stubs. There can really be no assurance that any plant will remain immune from disease, or pest but steps can be taken to reduce such possibilities.

Gardeners' queries, which can only be answered in this column, should be sent directly to Mr M. Lusty, 56 Wayside Avenue, Christchurch 5. Samples should be separately wrapped in a plastic bag with air boles. Provide representative, good-sized samples, and your name and address. A nom-de-plume can be used for publication.