GARDEN TOPICS

Ashburton Guardian, Volume 69, Issue 79, 13 January 1949, Page 3

GARDEN TOPICS

Pests and Diseases

• " - - Written for the "Guardian” by A. F.

MOEGAN, N.D.H. (N.Z.), F.8.1.H. (N.Z.)

In the constant war 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 l)e 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 scaled over. Overcrowding encourages certain plant diseases, while the excessive use of nitrogenous manures encourages 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 wants 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 useless in ridding a plant of one of the common pests such-as aphis or greenfly. Because of this, it is necessary to have some knowledge of the pest or disease to be checked and apply an appropriate spray.

Ins&ct Pests

Insect pests are divided into two groups: (1) Chewing insects such as the caterpillars of the white butterfly, grass grubs, porina grubs, leafroller caterpillars' and earwigs, 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, winter and summer oils and tobacco dust. Aphis includes the common greenfly, cabbage aphis, rose aphis, bean aphis and woolly aphis.

Plant Diseases (Fungoid)

These are quite a different proposition again, and just as the two 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 mildew, are common examples.

Combination Sprays

At times it is advisable to combine certain sprays to obtain control of both insect and fungus disease with the one application. Bordeaux mixture and lead argenate are often combined. Lime sulphur and lead arsenate can also be combined, but hydrated lime twice the weight of lead arsenate should he added to reduce risk of plant damage. Bordeaux mixture should never be combined with lime sulphur. Lime sulphur is more effective when combined with colloidal sulphur, and Black Leaf 40 can also be added. Black Leaf 40 can be used with summer oil.

Routine Work . t Staking' and tying dahlias, chrysanthemums', and other tall growing perennials should not be neglected and if show 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, giye 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 Avashed 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 aAvay from the hot sun. SoAA rings could include Iceland poppies, sAveet william, myosotis, Siberian AvallflOAver, hollyhocks, calendulas, delphiniums, lupin, gaillardia, pentstemons, pansies and stocks. With all these, early soAving ensures sturdy plants which can be put out before the cold Aveather sets in. Peonies should be lifted, divided, and re-planted (if the clumps have become overgroAvn) Avithout 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 doAvn a laAvn in early March, it is not too early to start Avorking the area, forking, tramping and keeping the surface hoed until soAving time. Such work will kill all weed seedlings and give a good fine tPth for the young grass.

Vegetable Garden Continuity of supply should he the aim of the home gardener at the present time, and failure to plant Avinter greens this month may result in a break in the supply during Avinter and early spring. Where such crops as savoy cabbage, broccoli, curly kale, brussels sprouts and leeks have not been planted, the planting of a suitable selection to provide supplies from late autumn until the ucav seasons’s crops have matured in late spring, should be done Avithout delay. Small soAvings of early peas, carrots, dAvarf beans and sAvedes can be made and should mature before Avinter; the measure of success Avith these Avill depend largely on favourable autumn Aveather, but are Avorth a trial. Other soAvings could include silver beet, radish, spinach and lettuce. Keep the lvoe going through all crops to keep cloavu Aveed groAvth and conserve soil moisture. There should be plenty of compost maturing just iioav and Avhen put through a. coarse sieve this material makes an ideal mulch for use in the vegetable garden. Spread between the i-oavs an inch, or so deep it Avill smother Aveed seedlings and bold the moisture in 1 lie ground. To prevent, lettuce and spinach from bolting to seed, keep them Avell watered apply liquid manure, or sulphate of ammonia at loz to lavo gallons of Avater every ten days. Runner beans will also require plenty of Avater to fill them out and keep the pods tender.