Gardeners’ queries

Press, 30 October 1981, Page 11

Gardeners’ queries

GARDENING

■ by

M. Lusty

?• Each year a Billingtom plnm gets infested with aphids on the ■young tender leaves. Early spraying with malathion or .menazon does not keep it under Control and the tree always looks jeglected. Second, I am unable jto grow decent green peas. I •spray them and give regular (liquid manure but after flower•lng, even though in good condition, they develop “drying off” 'and we usually only get one

picking. And, finally, my hyacinths are left in the ground al) year and they are all reverting to singles and small stunted flower stems. Should I lift them each year and is it worth keeping the seed for furture bulbs? “Keen Gardener” (Cbch). Some cultivars of plum are very susceptible to aphids and if these pests are not kept under control they can cause considerable debility under certain conditions. Malathion, and menazon in particular, will give control for varying periods, but it must be recognised that during the formative growth period in spring growth is rapid. Because of this the effectiveness of any controls is reduced and it therefore becomes necessary to spray

very much more frequently to deal with any problems, whether pest or disease outbreak. It is highly probable that the disease restricting development of the peas is pea wilt. Unfortunately, this can become a very pesistent soil-borne problem once it has become established, and requires a rotation of at least five years. There are resistant varieties such as Strategem, Aiderman and Epicure while Green feast, Onward and William Massey are listed as susceptible. Dusting of seed with thiram is strongly recommended. All hyacinths can be raised from seed. The species will usually come true from seed, but not the large flowered varieties which will take up to twice as long (six years) to come

into flower. Flowers tend to deteriorate over the years and bulbs are perhaps ’ best lifted annually, about November.

In our home we have a fruit salad plaint. It has been healthy until recently when small brown spots started to appear on the leaves, which are now turning yellow around the edges. Also small amounts of liquid ■ are dripping from , the leaves. L.A. (Chch). Fruit salad plant, Monstera deliciosa, also known as Swiss cheese plant, is one of the relatively easier-to-grow house plants, doing best in indirect sunlight, or semi-shade and moist soil which should be watered a little more frequently during the growing period. Mealy bugs, white fly, and scale insects and mites are occasionally troublesome, and some of these pests may cause “injury” to the extent that there' may be some exudation of sap. However, without examining the parts showing both spots and “liquid dripping from the leaves” it is not possible to offer much advice. Some of the pests mentioned tend to exude so-called honey dew and this can often give the leaves a sticky appearance. The enclosed, is a sample of weed that grows in my garden. I would be glad if you could tell me its name, and if there is a spray which will kill it. Could you also let me know bow to kill suckers from flowering cherries and japonica trees? S.T. (Chch). By the time your sample was received it was too dessicated for any attempted recognition. Samples should always be put into a polythene bag for posting and sent direct, not to “The Press” office. It is possible that either paraquat or glyphosate will control the weed safely, wherever it is growing. There is no chemical means of preventing the appearance of suckers from trees and shrubs which are prone to this habit, as far as is known. The best, and only way that I am aware of, is to rip them out at the source when they appear.

Could you give me any clue as to why my floribunda roses have shown no sign of growth yet? I did my pruning in August, but have had to keep trimming all the die-back. It is not just from where I’ve pruned, but often up the centre of the main stems. I tried hard pruning in the second year and much lighter pruning this season but to no avail. The roses have been well looked after in all respects, so where do 1 go from here? Daffodils are thriving in the bed. Could it be the fact that they are floribundas, or the fairly extreme temperatures. K.M. (Murchison). As always, when there is only a description of the prevailing problem without samples to go by it makes it difficult to provide

a definite answer. Roses are very hardy and will tolerate heavy frosts during the dormant season, however young growth in particular is susceptible to freezing conditions and will be cut right back. If this happens several times the stems can start to die back. Roses are also intolerant to prolonged wet feet which will cause them to eventually die irrespective of the attention otherwise given. There is a soil borne disease which can cause the death of roses and where this becomes established it is then necessary to sterilise or change the soil before replanting. Other plants may sometimes grow quite unaffectedly in the same site. There is a certain amount of difference of opinion on the pruning of floribundas but personal preference is for a semirenewal each year with lighter cutting back of the new shoots, harder for that which is older and total removal of anything over two to three years, but much depends on existing circumstances.

Please find enclosed a piece of conifer which has dead/diseased parts and we wondered if you could suggest a spray or treatment to bring it back to health again. It was only planted this winter; there are a couple of other newly planted conifers near by, can this trouble bp passed on to them? C.K. (Chch). This form of die-back is not uncommon with quite a number of conifers, certain species and g forms of Chamaecyparis- being particularly susceptible. Trees making good growth rarely suffer from the problem either way. An application of copper oxychloride should help to overcome the trouble.

Readers seeking answers to queries through this column should note the following points: Personal replies are not given. Fully representative specimens should accompany queries whenever possible. Specimens should be as complete as possible, should be individually enclosed in polythene bags, and should not be folded. As much relevant detail as possible should always be given, whether specimens are included or not.

Replies are not always printed immediately, but all queries will be answered in due course. Names and addresses must be included but noms de plume will be used if requested. All queries should be sent to M. Lusty, 32 Brockworth Place, Christchurch 1.