GARDENERS’ QUERIES

Press, Volume CXV, Issue 33792, 14 March 1975, Page 19

GARDENERS’ QUERIES

Could you please tell me the cause of the enclosed beans shrivelling; the first two or three beans are perfect, then this happens. Also could you identify this leaf. — "West Coaster" (Greymouth). Shrivelling of the bean could be due to a number of factors such as poor setting or insect damage, 'lire leaf is from a cucurbit, possibly marrow but not water melon. Further leaf samples and flowers would aid positive identification. I am enclosing a sample of nectarine. Could you please tell me the cause of the fruit cracking like this. We sprayed the buds twice with cuprox. — C. B. (Runanga). Bv the time the sample was readdressed it had gone completely rotten thereby Making it impossible to note the nature of the described symptoms. As there are several causes of “cracking" it is therefore not possible to diagnose the trouble or give specific advice. A bud movement spraying gives only temporary control of certain diseases and generally it pays to spray repeatedly at intervals throughout the seasons. Please find attached a few specimens of oxalis plants. I understand there are about six varieties of this weed and believe me I think this is the worst. In removing them I try with the utmost patience to uplift the whole plant and not lose any nodules. Could you tell me which this one is. — "Oxalis" (Spreydon). There are. in fact, some 800 species of oxalis. most of which come from South America and the American sub-tropical and tropical regions, though only a few are found in New Zealand. Tire species in question appears to be Oxalis latifolia. Apart from soil sterilisation there is as yet no really successful means of dealing with oxalis. My scarlet runners after a good start all developed a yellowing of appearance — little lines like mosaic as you can see from the enclosed few leaves. I have grown them for years i n some sheltered spot with wonderful crops until this season. — "Coaster" (KumaraAwatuna R.D.). A very severe infestation ol mites is responsible for the almost bleached appearance of the bean leaves and as such they can almost make the crop a write-off. In common with other

afflictions trouble .-an occur quite suddenly after tears of non-existence or apparently such and is precipitated in the ease of mites by warm, dry conditions. These pests will winter in various places including remains of the previous crop. The specific miticide kelthane is one of the best controls. Regular damping down of the foliage is also of some help as these pests do not like wet conditions. Would you please identify these insects, which I find on my grapevine and elsewhere. Does the insect bite or suck on plants or on human flesh. Would you describe the grub, which i presume to be the villain. — M. M. (Sumner). The insects are plant hoppers which are quite distinctive with their fresh green colouring and very steeply angled wings over the body. The nymphal form looks a bit like a grasshoper and has a brush-like protuberance emanating from the posterior end. The species is not known to be harmful. Could you please tell me how I can kill the roots and saplings of a lilac tree and an elderberry. They were intertwined and I have had them cut down to about ground level but do not know how to finish them off. — N.H. (Christchurch). The most effective material for controlling woody species are the picloram mixtures containing in addition either 2,4-D or 2,4,5-T. Alternatively esters of either 2,4D or 2,4,5-T mixed with diesel oil can be used to swab the stumps. You advised a reader to dig up a rose bush to get rid of twitch. An easier way would be to spray the twitch with phyta--10I; it would not harm the rose. — J.D. (Ashburton). i Thank you for your comments. However, the problem is not J quite so simple when twitch has ! actually gown “Through” a ! plant. In such a case it would be ' impossible to spray the offending weed without also contaminating the desired plant which must i naturally be resistant to the ! applied herbicide. Phytazol, of ■ which there are currently two i different formulations available for different situations, is a nonj selective weedkiller for use in the control of grasses and braodleaf weeds but alhtough it will not damage nearby roots of most desirable plants it must not be allowed to come into contact i with lawns, shrubs and flowers, i either directly or as drift.