Gardeners’ queries

Press, 22 June 1984, Page 15

Gardeners’ queries

Mike Lusty wishes to apologise to readers for any delay in answering their queries. Illness has prevented more prompt attention to their problems.

Could you tell me what has caused the enclosed rose buds to go brown as they have? Only one stem from the recently planted bush has produced such buds although the stems have remained green. A while ago we had a similar experience only on that occasion all the buds browned off. Also, could I grow a frangipani here as the other day I took a chance and bought one? 1.8. (Sumner). The browning of the rose buds has been caused by the presence of botrytis. This disease, frequently referred to as blast, is not uncommon and there is also some varietal susceptibility. Incidence and

carry over can be considerably reduced by removing and destroying all diseased plant material and regular spraying with such fungicides as thiram or triforine. Frangipani requires consistent warmth and good light to thrive and flower. As such it cannot really be regarded as other than an indoor plant here.

Could you please identify the enclosed plant and tell me how to kill it? I have tried Network, which made no impression on it. E.M. (Cheviot).

The plant in question is hydrocotyle. A most important aspect of any recommendation regarding control centres on the location in which the plant is growing. Amitrol-T is suggested for areas other than lawns, where various combinations such as MCPA plus MCPP have given variable results, particularly if not repeated.

Could you please tell me what to grow in a tub (half barrel) in a very warm and dry position, against the house, facing north and getting the sun all day? L.J. (Blenheim). Probably the most overlooked consideration in attempting to grow plants in tubs, especially in very warm situations, is the need to provide a good moisture retentive rooting medium. Insufficient consideration of this aspect has probably accounted for very many of the failures with tub culture. Plants which could be grown in a tub situated in a very warm sunny location include hibiscus, citrus guava, bougainvillea, narangilla, cistus, nerium, Xero-nema callistemon.

What can be done to kill

moss on a drive? Poisonous sprays could be harmful to animals, so I don’t want to use

them. What about common salt, ammonium sulphate, or ferrous sulphate? I started to remove the moss by hand from the asphalt drive, which has small stones embedded in it, and an accummulation of dust over the years — but this is a tedious, and a big job. E.S. (Chch).

The most effective time to control moss occurs when it is in active growth, which is predominantly from late winter into early spring. Ferrous or iron sulphate sprinkled over the entire mossy surface, or watered in, can be quite satisfactory. Alternatively, one of the proprietary moss killers, which generally contain sodium pentachlorphenate, should be applied. Provided that application is made with care there should be no problems at all with animals being harmed.

Could you please identify

what dreaded disease has attacked these pears? It has stunted their growth and causes them to rot. What is the best form of treatment? A.K. (Chch).

Black spot is responsible for the stunting of the pears, although the rotting would appear to be a secondary infection. Once it has become established, black spot can become a very persistent and debilitating disease which can take considerable time and persistence to get under control. Bordeaux mixture, or one of the copper-based materials, are still amongst the best forms of control. Initially, all infected fruit and leaves should be raked up and burned. The tree could be sprayed now, again in about a month's time, at bud movement, and at intervals during the spring.