GARDEN TOPICS

Ashburton Guardian, Volume 70, Issue 71, 5 January 1950, Page 3

GARDEN TOPICS

PESTS AND DISEASES

Written for the "Guardian" by A. F. MORGAN. N.D.H. (N.Z.), F.R.I.H. (N.Z.). In the constant Avar waged by the gardener against plant diseases, the golden rule should be clean gardening. This involves the removal and composting of all unwanted vegetation which is free from disease, and the burning of infested crops. Crop rotation is another important item in the continual fight, for it breaks the continuity of conditions suitable for certain pests. Vacant plots should be dug over early in order to keep the soil sweet, and periodic liming will greatly assist, mainly in the control of clubroot. Trees and shrubs should be gone over regularly, diseased wood removed and the wounds sealed over. Overcrowding encourages certain plant diseases, while the excessive use of nitrogenous manures encourtges soft, sappy growth which is then liable to attack from insects and fungoid diseases.

The choice of materials now on the market for the control of garden pests and diseases is somewhat confusing to the average gardener who Avants to keep his plants reasonably clean. In addition to this it often happens that quite the wrong kind of spray is purchased to control a particular pest or disease. Certain spraying materials are manufactured for the control of a particular disease and may be quite yseless in ridding a plant of one of the common pests such as aphis or greenfly. Because of this, it is necessary to have some knoAvledge of the pest or disease to be checked and apply an appropriate spray. Insect Pests Insect pests are divided into two groups: (1) Chewing insects such as the caterpillars of the Avhite butterfly, grass grubs, porina grubs, leafroller caterpillars and eanvigs, to mention but a few. Here, because of the feeding habits of the pests, a stomach poison is used, the chief ones being arsenate of lead, and paris green. Derris dust is also effective. (2) Sucking insects, such as aphis, mealy bugs, and scales. In this case quite a different type of spray is used, namely a contact or smother spray such as Black Leaf 40, kerosene emulsion, Avinter and summer oils and tobacco dust. Aphis includes the common greenfly, cabbage aphis, rose aphis, bean aphis and Avoolly aphis. Plant Diseases (Fungoid) i These are quite a different pi’oposition again, and just as the tAvo types of insect pests require different kinds of spray, it is necessary to use a “fungicide spray” such as lime sulphur, colloidal sulphur, dry sulphur, or a Bordeaux spray to control many common plant diseases. Rose 'mildew, black spot, rust, leaf curl, brown rot, apple powdery mildeAv, are common examples. Combination Sprays « At times it is advisable to combine certain sprays to obtain control ofboth insect and fungus disease with the one application. Bordeaux mixture and lead arsenate are often combined. Lime sulphur and lead arsenate can also be combined, but hydrated lime tAvice the Aveiglit of lead arsenate should be added to reduce risk of plant damage. Bordeaux mixture should never be combined Avith lime sulphur. Lime sulphur is more effective Avhen combined with colloidal sulphur, and Black Leaf 40 can also be added. Black Leaf 40 can be used Avith summer oil. Routine'Work Staking and tying dahlias, chrysanthemums, and other tall groAVing perennials should not be neglected and if slioav blooms are required it •will be necessary to do a certain amount of disbudding. Before feeding such plants either with a complete fertiliser or liquid animal manure, give them first a good soaking Avith clean Avater if the ground is at all dry. Top dressings of fertiliser are of no use to plants unless the materials are washed Avell into the soil and dissolved in the soil moisture. There is still time to make soAvings for next spring and summer displays, but it is advisable at this time of the year to soav in boxes which can be placed aAVRy from the hot sun. Sowings could include Iceland poppies, SAveet william, myosotis, Siberian AvallfloAver, hollyhocks, calendulas, delphiniums, lupin, gaillardia, pentstemons, pansies and stocks. With all these, early sowing ensures sturdy plants which can be put out before the cold weather sets in. Peonies should be lifted, divided, and re-planted (if the clumps have become overgroAvn) without delay as they have a short resting period. Once this is done they are better left undisturbed for several seasons.

Where potatoes have been grown in an area preparatory to sowing, down a lawn in early March, it is not too early to start working the area, forking, tramping and keeping the surface hoed until sowing time. Such work will kill all weed seedlings and give a good fine tilth for the young grass. Vegetable Garden Continuity of supply should be the aim of the home gardener at the present time, and failure to plant winter greens this month may result in a break in the supply during winter and early spring. Where such crops as savoy cabbage, broccoli, curly kale, brussels sprouts and leeks have hot been planted, the planting of a suitable selection to provide supplies from late autumn until the new season’s crops have matured in late spring, should he done without delay. Small sowings of early peas, carrots, wdarf beans and swedes can he made and should mature before winter; the measure of success with these will depend largely on favourable autumn weather, but are worth a trial. Other sowings could include silver beet, radish, spinach and lettuce. Keep the hoe going through all crops to keep down ween growth and conserve soil moisture. There should be plenty of compost maturing just now and when put through a coarse sieve this material makes an ideal mulch.for use in the vegetable garden. Spread between the rows an inch or so deep it will smother weed seedlings and hold the,moisture in the ground. To prevent lettuce and spinach from

bolting to seed, keep them well watered; apply liquid manure, or sulphate of ammonia at, loz to two gallons of water every 10 days. Runner beans will also require plenty of water to fill them out and keep the pads tender.