Gardeners' queries

Press, 24 April 1986, Page 8

Gardeners' queries

GARDENING

by

Mike Lusty

I recently planted some green broccoli plants. They grew to a height of six inches then wilted. When I pulled them out I found that they were club rooted. What do you do to prevent this happening in the future? “Wondering” (Hokitika). Club root is a soil borne fungus which favours acid soil, and is a disease which attacks only crucifers; in the absence of a suitable host it can remain viable in the soil for up to seven years. It can be a debilitating infection which can cause the death of young plants as has occurred in this case. The application of lime, preferably in some other form than ground limestone — for instance, hydrated lime — is recommended. It may take at least a year before such treatment has effect. An alternative control is to drench the soil with thiophanate-methyl prior to transplanting. The roots of the young plants could be dipped in a preparation of the same fungicide. I have enclosed a sample of a weed now infesting my front lawn. Applications of weed killer have been unsuccessful in controlling this weed. Could you identify the week, and if possible recommend an appropriate deterrent. J.K. (North Beach). Once again we are confronted by the current and persistent lawn enemy No. 1, hydrocotyle. Unless control is. effected at a very early stage of development, it generally requires persistence to gain control of this weed. Recommended herbicides include bromacil, and the combina-

tions of bromoxynil/ioxynil/ mecocrop, and 2,4-D/piclo-ram, all of which are available in a minimum of 5-litre :ontainers only. Less effective is the mixture of 2,4-D and dicamba, but this can be purchased in smaller amounts. Whatever preparation is applied, it is recommended to add a little wetting agent. Would you give me the cure-all for mercury bay weed which has been identified as being in my lawn? It is a bright green, smallleafed plant which grows extensively in the damp parts. R.M. (Chch). Mercury Bay weed, Dichondra repens, also known as Kidney Weed or simply dichondra, can be controlled with either the combination spray of 2,4-D/dicamba, or 2,4-D/picloram. Best results are obtained with applications made at the flowering stage in the spring. A wetting agent should be added, and care is needed in the application of both these herbicides as they can damage fine turf. My,/ beans suddenly col--4' 1

lapsed and withered as in the samples. I do not like spraying plants when they are in flower as I have wonderful bees all over the garden. This happened last year when the season was so dry — I cleaned up the area to the best of my ability, but there are always a lot of affected leaves left on the ground. I watered Jeyes Fluid into the ground. Could you advise me about a winter spray for the ground? J.H. (Pigeon Bay). The shrivelled nature of the leaves made it impossible to determine the cause of your trouble. Severe infestations of mites will cause intense chlorosis of the leaves, and under stress, such as hot sunny weather and dryness at the roots, wilting and even some leaf shrivel can occur. In this case, disease is suspected as at least partially responsible for what has been described. Mites can be controlled with an acaricide such as dicofol or tetradifon. These pests over-winter on fallen leaves and other debris so it is sound policy to have a good clean-up. Insecticides should not be applied to plants in flower because they can damage bees, as you have rightly stated. Enclosed you will find a sample of plant growing in my garden. It appeared suddenly in'January since when It has spread about 50cm over the ground and is about 30cm high. The creamy white flowers with a purple centre only last about one day following which they turn into these lovely T

pods. A lot of people are fascinated by it R.J. (Rotherham). The plant is Hibiscus trionum, the smaller flowered of two native hibiscus. Of annual or biennial habit, flowering is continuous over a long period although the individual blooms do not last long. Both species deserve to be more commonly grown as the flowers are very attractive. Gardeners’ Queries should be sent directly to Mr Mike Lusty, 56 Wayside 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-plutne can be used for publication.