Gardeners’queries

Press, 27 March 1981, Page 9

Gardeners’queries

My cabbages and cauliflowers have been infected by club root. The roots are swollen and tuberous, in some cases rotting in the ground, and the plants have either died or done very poorly. The ground had been fairly heavily dressed with fowl manure. Could you please tell me what chance I have of ever growing cabbages and cauliflowers again, and what steps to take to make this possible? R.L. (Christchurch). The description given relates to extreme infection of club root, a disease not easily got rid of. Club root spores have extremely long viability in the soil, and because of the ease with which the disease is transported, rotation, and the destruction of infected crop refuse is essential. Infected brassicas should never be used for composting, as the fungus vvill survive and its distribution assured whereever the compost is applied. This disease is greatly reduced in less acid soil, and the application of lime is a general recommendation. Possibly more directly effective is the addition of about 200 ml (one tea cup) of benomyl to every planting hole in addition to dipping the roots in the solution before transplanting. I should be grateful for your recommendations as to the best use to make of our small vegetable plot, measuring approximately 5m x 2.5 m- Having been used until recently to spreading ourselves in a large section we are finding it difficult to think small. In addition to this plot, we have a warm northfacing bed for tomatoes and say, lettuce, and a narrow bed along the fence line for growing herbs. M.P. (Christchurch). There are several considerations to be made in deciding how best to utilise your vegetable plot, and this could really have more general application. List the vegetables which you prefer and which will do well. Restrict your selection to those which do not require too much room, and those which are useful to have on hand, such as

parsley. Avoid growing too much of any one thing and rather attempt small, successional sowings and/or plantings. Try to keep the taller growing crop's to the back so that they do not shade the smaller ones. Many vegetables can in fact be grown up off the ground thus, saving space; for instance pumpkins and peas. Potatoes and strawberries can be grown in drums or other forms of containers. Cloches and other protective devices are very useful for forwarding crops particularly at less favourable times of the year. There are smaller and/or more erect growing forms of many vegetables, such as Cos lettuce, which take up less room in the garden. Another consideration for small areas fs to grow only the less common vegetables. Hygiene, by which is meant pest and disease control, must be more strictly observed. Although rotation will be difficult to follow, some form of variable planting can be achieved with a little planning, a 'useful procedure in itself. And don’t forget to incorporate plenty of organic material of a well-rotted nature whenever possible. I have enclosed some leaves and beans from my runner beans. I should like to know what is the matter with them. At the end of January the leaves started to get a faded fawn look, and I was told that it could be mites, so I sprayed with malathion. On my return after a month the formed pods were hanging on leafless vines. Remaining beans were pulled off and burnt' but the disease has formed on the regrowth and I feel I should dig out the old plants and plant barley as this disease affected them fast year as well. I hope you can advise me on what to do — beans are the mainstay of my vegetable garden. J.H. (Banks Peninsula). Your beans have been very badly infested by mites. These pests favour warm dry conditions, can severely debilitate bean crops, and h?ve been extremely prevalent this summer. The best control currently

available for home .garden use is teiradifon which is a specific-acari-cide; it should not be applied closer than seven days to harvest Malathion is not as effective for. this purpose. Looper caterpillars are another pest to watch for at this time of the year and this voracious caterpillar will make massive inroads into beans, and other vegetable crops, if not controlled — Carbaryl being most effective in this respect. Could you identify the trouble with my tomatoes from the enclosed leaves and fruit. About half the crop has been wasted because of this trouble. Firstly, there have been masses of tiny white flies which take off as soon as you touch the leaves, and these have also been troubling other vegetables in the garden. Then there have been caterpillars from minute size to very large, and together these pests have eaten away most of the foliage, and ail stages of fruit. Other fruit is affected by soft patches. C.R. {Christchurch). White fly feed by sucking the sap from the plant causing one form of debility. The caterpillars, of which there are likely to be two species on your tomatoes, judging by the type of damage — the looper and the tomato caterpillar — reduce the leaf area, thus weakening the plant, and also exposing fruit to sun burn. The best material for use on your plants is acephate, which has the capacity to control not only the caterpillars but also the more difficult to control w-hite fly. It should be noted that this wettable powder precludes harvesting until seven days following application. Infection will often penetrate fruit which has been eaten by insects. White fly populations have not been heavy this past few months and it is possible that there has been a build up of these pests. It pays to try and get as good control as possible, and apart from repeating the spray, remove any weed growth and unwanted vegetation which may harbour them.