GARDENERS’ QUERIES

Press, Volume CXV, Issue 33815, 11 April 1975, Page 13

GARDENERS’ QUERIES

I have sprayed my apples during the winter with arsenate of lead twice; Bor deaux, cuprox and winter oil several times; captan and pestmaster spray at green tip not blossom until January and look at my result. All my plums and nectarines got brown rot and they all get the same treatment. The codlin moth is still prevalent in the apples. I spray all my roses with Yates Rose Spray and added karathan for powdery mildew and rust, and they still have it. I sprayed the grass with phytazol A and it only died down in the orchard and I want to kill it. What spray will kill it?—J.C. (Christchurch). The fruit is most certainly in exceptionally poor condition, the plums having brown rot and the; apples displaying symptoms of black spot, brown rot, leaf roller, mites and poor fruit set.! It should not be necessary to apply more than one winter; clean-up spray and this could' comprise winter oil, Bordeaux] mixture and lindane. A thorough: application is needed. There, should be no need for any form; of additional oil sprays on pipi or stone fruit other than in winter and is usually not vital; on the latter at any time. Captan' is an adequate fungicide I although it has a short residual ’ life; it is widely used for the control of many fungous diseases such as brown rot but as this j disease can appear and spread; in a very short time, even after the fruit has been picked, it is essential to maintain a good cover control. Early in the season arsenate of lead and' D.D.T. will protect against codlin j moth but close to harvest■ carbaryl should be used as this; lu.s a ve.y short waiting period.; D.D.D., diazinon or carbaryl control leaf roller. Kelthane is a specific miticide. Timing, correct preparation and adequate spray coverage will give good control and satisfactory results but weatner will greatly influence effectiveness, the need to repeat, sprays and the prevalence of some of the pests and diseases. Rust can be very persistent and difficult to control on roses and zineb is generally the preferred treatment. For a quick knock down of grasses under fruit trees paraquat is ideal, but for killing grass dalapon should be used. Long-term treatment is achieved by using a material such as cassaron which will also control broad leaf weeds. To be effective phytazol must be applied at the strength and time indicated by the manufacturers; reaction to it is not spontaneous but gradual. I had a load of top soil delivered for sowing an autumn lawn but now find that the whole area is netted with a root and leaf system of the enclosed plant How will I get rid of the weed and might it still be possible to sow the grass this season? — L.G. (Sumner). The weed in question is sheeps sorrel which has a creeping underground stem. Heavy intestation of this weed is regarded as indicative of a poor soil such as where heavy or continuous cropping has been carried out. Probably the most effective treatment at this stage, and with a view to late autumn sowing, would be to apply amitrol T. At least two to three weeks should elapse between application and subsequent cultivation. If the soil is light, sowing could be made in about two weeks after thorough cultivation, but more time is needed for heavier ground. It should be possible to sow as late as June if you are in a frost-free position. This plant is a stranger to us. We think it was washed down in a flood — all people in Reefton have strange plants in their gardens since the flood. — B.W. (Reefton). • The plant is known as summer i grass, an annual which shoulc ' not be allowed to establish It sell 1 tn any garden. Although it 11

only an annual it has a creeping underground stem and also is renowned as a very profuse seeder.! Would you please tell me what is the matter with my i rubber plant, which is about four years old? Apart from the enclosed yellow leaf another has a small brown patch on it i and a third one several patch- I es. The plant seems to be thriving. 8.5.3 is sometimes added to the water when ; watering. How often is it advisable to use a pot plant food? — < M.D. (Christchurch). It is generally difficult to pinpoint the exact cause of com-; plaints such as this without, seeing the plant and situation in which it is growing. Over-water-! ing is the most usual cause for yellowing and the spotting could ; be associated also with the posi-' i tion in which the plant is kept —! too hot, or dry air, scorch, etc.■ I Feeding could be on a fort-: ■ nightly basis during the growing ■ season only and gradually taperiing off. I have a poinsettia plant • which I cut back and repotted ' . last winter and it has grown J very tall but the leaves are ‘ showing signs of turning red. I ! always keep water in the dish 1 which I have the pot standing in, as if I do not do this the leaves turn yellow and drop off. It certainly looks healthy but please tell me why the leaves are not turning red. — ' H.W. (Christchurch). The colouration of poinsettia is due to the appearance of bracts which develop with the flowers, • they are not leaves in the true , sense. Poinsettia are more dlffi- ■ cult to maintain than other ; house plants. It is essential to avoid letting them dry out but : they should not be kept in a ■ saturated soil. Even temperature, avoidance of draughts, plenty of light after bud initiation and not i a dry atmosphere, are also neces- ■ sary. The growing point should : be pinched out when the plant is about 30cm to induce bushiness. Il is a very bad policy to keep ‘any pot plants standing in water. Could you please tell me of a satisfactory method for killing . elderberry and wild plum trees without removing the roots. : The latter is impossible because they are growing between a drive and a concrete sided drain. The trees have been cut to ground level without success. — N.F. (Christchurch). It is futile to cut down to ; ground level both elderberry and plum in the hope of killing them as they will only regenerate again. The best chemical for killing these trees is one of the proprietary preparations containing picloram and either 2,4, 5-T or 2. 4-D. The stumps should be well swabbed preferably frilling the bark and liberally painting the exposed wood with the preparation. Dicamba plus 2. 4-D is also now used for killing some woody plants. All preparations mentioned are hormones and must be used with great care.