READERS' PROBLEMS:

New Zealand Herald, Volume LXXVI, Issue 23489, 28 October 1939, Page 8 (Supplement)

READERS' PROBLEMS:

Rhododendron Trouble.—Could you please inform mo what to do with a fragrantissima or Pearl rhododendron that I have? It has been plunted for 18 months and has had well rotted sheep manure placed under it, and it is growing jn pumice soil in a sheltered position. It is high country with snow here and the shrub was not covered. The shrub just exists but docs not grow.—"Constant reader," Main Trunk. The puinice soil is about the worst inedinra possible in which to grow rhododendrons. Your only hope will be to procure a quantity of leaf soil from tho bush and incorporate plenty of this with the soil in which tho plant is growing. Also give a good topdressing every spring of tho same material. Idesia Polycarpa.—(l) I have two plants of this tree grown from soed. Will you kindly inform mo how to distinguish between male and fomalo plants, and must they bo planted closo to each other? Does tho treo grow to any great height? I havo not Been a large specimen of tho tree and would therefore appreciate any information regarding it. What country is it n nativo of? (2) I have a waratah which bloomed this year for tho first time. Somo months ago I noticed that a caterpillar had bored into tho bud, with tho result that tho bloom is a poor one. Will I havo to tako action in future to protect the buds against pests?—"Polycarpa," Papatoetoe. (1) It will not bo possible to distinguish between tho inalo and female plants until they flower. Tho staminate, or male flowers aro slightly larger than tho pistillate or female flowers. It is not necessary to plant close, to each other; so long as they aro in tho samo garden- pollination will bo effected by tho wind or bees. In its nativo habitat tho tree grows to 50 feet. It is a nativo of China and Japan. There aro no trees of very largo sizo ill tho Dominion as It is only within recent years that the treo lias been introduced. (2) It should not bo necessary to spray tho waratah buds as a precaution against caterpillars. It just happened to-bo your bad luck this season with only ono bud. Minoral Deficiency.—Could you give me information as to tho cause of leaves and fruit of a blood plum falling off? Last year tho..plums grew to about half size, then fell ...off. At present tho leaves are shrivelling and falling, also most of the blossom. Enclosed are samples. This tree has previously borne well. Your columns havo been a great help to m 0 Epsom. ' Th'o cause is a deficiency of lime and nitrogen also. Give a good application of lime and next spring, before the blossoms open givo an application of sulphate of ammonia, one pound, for each year or age of the treo. An application of sulphate of ammonia now will help [Jio tree to make good foliage, but will not savo your crop of fruit tills season. Shot Holo Fungus.—(l) I ain enclosing a specimen taken from a laurel tree. The halves of two trees only seem to bo afTected. The other halves aro in flower and appear quito healthy. Do you consider that frost may have caused the condition, or lias some disease attacked the trees? (2) Could you advise a suitable climbing plant for a recently installed trellis work? I .want some'thing which will flower most of tho year. Would Poulsen roses bo suitablo?—"Laurel," Frankton. (I) Tho laurel is affected with Rhot holo disease, which leads to die back. The best treatment is to cut away tho affected portions into sound wood, then spray tho remainder with Bordeaux powder one ounco to ono gallon of .water, or limo sulphur 1 in 80. Laurels can bo cut fairly hard at this season of tho year and will mako now wood from the base very freely. (2) Poulsen roses would not bo tall enough to cover a trellis unless it is a very low ono. If the position is a warm ono Thunbergla Gibsonii will givo flowers for the best part of the year. Tacsonia mollisisima will also flower most of tho year. Among climbing roses there are a largo number which of course flower in their soason. Paul's Scarlet Climber and Mrs. Arthur Curtis James (golden yellow) aro a good pair. Falling Lawsonlana.—(l) I am soon back again with more troubles, and must thank you for your help of a few weeks ago. I havo done as advised and expect improvement. We have been disappointed to see some of our lawsonlana go first brown and then, bare at tho baso. Will you advise the cause of the trouble and tho remedy; also how to prevent it spreading? (2) What is tho cause of weak stems of long-stemmed flowers, particularly Iceland poppies, gerberusand tulips? (8) What

is wrong with my tulips? Somo showed tiny flowers when tho leaves were just pushing through the soil and did not develop properly. Will these bulbs bo any good for another season, or shall I discard them? (4) Is limo detrimental to hibiscus, luculia, azalea and ceratostigma? (6)."1s compost manure? —"Kowhai,"' f laucaiiga. • (1) There may bo several reasons for the lawsoninnu failing in places. If the affected trees aro in tho low-lying places, tho most probable cause would bo waterlogging in winter. Another reason'may be that the trees are attacked by one of the many root rots which affect the conifer tribo. It would be advisable to examine the baso of tho affected trees and observe if there is an exudation of resin, so that tho specific disease can be determined. (2) Lack of sufficient potash. (3) For some reason the tulips have failed to make sufficient root, either through too shallow planting or the incidenco of some disease such' as basal rot. Lift the bulbs and, after .drying in the shade, plant next April, with Evo inches or soil over tlie tops of tho bulbs. (4) Lime would bo detrimental to the azaleas only of tho shrubs mentionod. (5) Compost made from tho decayed portions of vegetable matter could bo considered manure, as well as that composed of animal residues. A compost for potting purposes, on tho other hand, is composed mostly of soil and sand. Identification of Shrub.—Would yon identify tho enclosed specimon of shrub?— "Shrub," Dargavillo. Exochorda grandiflora.

|To Correspondents. Unfortunately, ; lack of space necessitates replies to • numerous garden problems being held j over each Week. These Will all ap- • pear in due course, but in any case j of urgency a stamped addressed ; envelope will bring an immediate ] reply.—"Kcpos."

Some Queries Answered

Quince Rust.—(l) "What should I spray a (luinco with to combat rust? (12) Could you givo address of Holland firms who could supply bulbs?. (1) Spray with limo sulphur 1 in GO just before tho blossoms open, and again after tho petals have fallen. (2) Addresses can bo sent on receipt of a stamped addressed envelope. Identification of Creeper.—Would you advise tho namo of oncloscd creopor?—C.E.D., To Puiio. Akebia quinata, nativo of China and Japan. Identification of Plant.—Could yon identify the enclosed plants? In case tho plants arc too withered when they reach you, it has a .s'niall yellow flower and looks as if it would develop a strong tap root. Is tho plant annual, biennial or perennial?—J.G., Pnrakai. Tho plant is Sisymbrium officinale, commonly called hedgo mustard. Plant is un annual. Trimming Hedges.—Enclosed samples of a prickly hedge flower, and also a shrub. Which is tho best tinio ,to trim them, now, or when tho blossom is gone?—H.B., Taranaki. (1) Blossom of prickly hedgo is Acacia verticillata; tho best tirrio to trim is immediately the flower is past. (2) White flowored specimen Is Tagasasto, commonly called tree lucerne. This is a quick grower but does not last many years ajid if cut into the hard wood will dio back. Any trimming should bo confined to tho youngest shoots immediately after flowering. Tingitana Iris. —(1) Could you adviso tho correct method of treating Tingitana iris? I havo largo numbers, but in spite of different methods of treatment, they do not flower well. (2) When should Iceland poppy seeds bo sown uiui tho young plants set out for winter flowering? Aro there any strains bettor suiled for winter flowering than otliorH ?—M ,E. f{., 1 'a putoetoe. (1) Lift the bulbs when tho foliage ripens and expose In (ho full sunshine for the summer to be ripened. lloplant in autumn like shallots, by just pushing into tho soil. Some soils do not suit tho tingitana so woll as others. (2) Sow tho poppies in Novoinber or December. Keen as cool as possiblo, no heat is required. Tho plantß should be ready

y for planting out in March as soon as a eootl K rain falls. Yes. r Soil Pests. —I am an interested follower of 0 your valuablo notes and wonder if you can j suggest a remedy to rid niy garden of insect i. life? The most prominent are (a) ground lico; (b) earwigs; (c) centipedes: (d) slaters; e i'-> slugs. The soil is lipht volcanic and is :I bordered on two sides by a passion vino j trailing over a board fence. Small wliito in--1 sects—l call them ground lico—are attack--3 ing tho roots of my tomatoes and have ncs counted for quit.o a number or plants to date. . Would a spray save them?—H.P.G., Epsom. 1 Tho small white insects aro Collembola, i and usually live on decaying matter. A soil 3 fumigant is needed to pet rid of them. A l pood mixture to fork into tho soil when J digging over, is limo four parts to horticul- , tural napthalene one part, at tho rate of four [ ounces per square yard. At the present time • napthalene can be hoed In at tho rato of one ouneo pqr square yard. The centipedes do no , harm, as they live on other insects, but tho ■ earwiffs, slaters and slugs should be poisoned. ro seven pounds of bran add quarter pound of Paris Green. Moisten with water in which two tablespoons of treaclo iiavo'bcen dissolved. Place in small heaps at dusk. Tho bait is inado more attractive by the addition of chopped-up lemons. There aro also good slug remedies on tho market and theso should bo given a trial. Sowing Troo Seeds.—(l) Would you advise tho best way to raise pinus - insignia from tho conesP (2) Can you identify tho fruit treo from specimen enclosed P Tho treo Is about ton years old and has never been in flower. Is tho treo worth troubling with?— "Inquirer," Ngatca. (1) Gather tho ripo cones and placo on a sheet in a warm placo till the cones open and release tho seeds. Sow in drills similar to vogotablo seeds in well worked ground. Tho seeds can bo sown at tho present time. Shade tho beds and seedlings till tho seedlings are of kood size, then transplant in nursery rows in.autumn. (2) Apple, probably a seedlinpr. Iho tree could bo Krafted over with a kriown pood variety, otherwise if is not worth troubling with. Pest Control.—ls thero anything which can bo sprayed on vegetables and plants to keen tho snails awayP I have been sprinkling unslaked lime around tho plants, but after a shower of rain tho snails go over tho liine. Could cabbado plants bo sprayed with anything to kcop off tho while butterfly?— ' Cabbage,"- Papakura. Arsonato of lead, half an ounco to one gallpn of water can bo sprayed over tho plants and vegetables, but should not bo used on vegetables that aro likely to bo used for consumption within three weeks. Permanpranato of iiotash crystals placed round choice plants will protect them from slugs and snails, but will need to bo renewed after rain. Thero aro also several excellent proprietary sluk and snail killers on the market which should bo tried. Dust tho cabbaßo plants with sulphur threo parts to common popnor ono part, or spray with tho arsenate ' of lead. Brown Rot Infection.—Could you advise what is wrong with m.v Burbank plum trees? Tho last threo years we have had no fruit. Although tho trees aro a blaze of healthy blossom ono day, within two or three days the whole tree is brown and dried up liko the specimen. Last year and the year beforo wo sprayed and thorißht tho result was duo to tho spray, but this year without spraying tho rosult is tho same. There have been no cold winds or hail to spoil tho bloom. Could it bo tho fault of the soil? Tho troublo is tho blossom Infection stago of brown rot. If you have any peaches infected with brown rot, see that all tho mummified fruits are collected and burned by winter. Also during winter romovo any brown rot cankors on tho twins of plums and peaches. Spray with winter Bordeaux before tho buds burst and givo an application of sulphate of potash in oarly sprins before tho buds open.