Gardeners’ Queries...

Press, Volume CII, Issue 30057, 15 February 1963, Page 6

Gardeners’ Queries...

Enclosed Is a petunia plant which seems to be obviously Infected by some disease. My Brussels sprouts are similarly infected for the first two or three inches of the stem. The soil Is clay with a scarcity of organic matter. Could you tell me what the disease is, and would you also recommend K tentative treatment?— ■R. (Reefton).

Our apologies for the delay in answering your query. It has not been an easy matter to determine the cause of the trouble, and it has involved considerable research to determine the cause. Before committing ourselves we would appreciate further specimens, including some of the Brussels sprouts. It may be that the normal roots of the plants are unable to function, perhaps because of the heavy soil, or poor drainage, or there may even be a deficiency. This is stimulating the plant to produce new roots to carry out the functions of its normal ones.

I have a 12-year-old apricot tree in my garden that is 14ft high. In all the time that I have had it I don’t think that it has borne two cases of fruit. The tree Itself appears to be very healthy. I feel like chopping it down and replanting with peach trees. What would you recommend? R.B.A. (Christchurch). As your tree has been a constant poor cropper over the years there seems to be little point in retaining it. I would suggest that you remove it and replace it with the peach trees which you suggest. I have a section which is at present planted with potatoes. It is, however, heavily Infested with Californian thistle and I would like to know how this can be eradicated.—G.EA. (New Brighton). Californian thistle is a perennial with a creeping underground habit and has proved difficult to control. It Is suggested that you cut the thistles now to stop them seeding. You should not leave the thistles lying on the ground for the cut plants can produce seed; collect them up and bum them. After the potatoes have been lifted, spray regrowths on the thistles with weedazol TL when they are from four to 10 inches hign. It will probably be necessary to spray further regrowths again. Due to the claimed short persistence of this chemical in the soil, the ground becomes usable again about one month after application. 1 am forwarding a sample of apricot leaves and fruit in the hope that you can tell me what is wrong with them. Black Leaf 40 and orthoclde have been used as sprays on several oeca-

cion* but to no avail. Ono branch has all yellow leaves while most of the others have numerous holes in them. The fruit seems to be eaten by something, also. There is also something attacking my Peace rose (several leave* are enclosed for diagnosis). Correct times for spray applications would also be appreciated^—“Enquirer" (Geraldine).

If you will excuse th* comment, your apricot tree seem* to be in a neglected state. First, the fruit is being eaten by leaf roller caterpillar; this can be controlled bv applications of D.D.D. from November onwards. Thinning of fruit before spray application will give better control where the tree is heavily laden. The perforations in the leaves are caused by the fungus disease, shot hole. Bordeaux applied at leaf fall and again at bud movement, to be followed by' captan or thiram at the pink bud, full bloom and petal tall stage, will give adequate protection against this disease and also other fungus diseases. It is difficult to say anything definite about the isolated branch which is bearing yellow leaves. It is possible that the tree needs feeding and a general fertiliser application at the rate of up to 121 b per tree, depending on the age of the tree, would be beneficial. This would be best applied in late winter so as to be available when growth start* in the spring. There are two diseases present on your roses. One is black spot, which can be controlled by applications of captan; in your case I suggest that you apply this at intervals of two weeks. The other disease is rust, and zineb at similar intervals should give control. The writer* of this column eannot enter into private correspondence on matters relating to this page. All Gardeners Queries will be answered only through this page. Last year I planted some Dutch Glory lilies and they gave a very good display. This year, although the bulbs have not been disturbed, they have not moved. Why is this? Could you tell me what to use to control mildew on roses that will not disfigure the foliage?—“Glou-

cester Street.” If no growth has appeared from your lily bulbs, It would appear likely that they are dead. Karatnane will control mildew on roses. Providing the instructions are followed and spraying is carried out in the cool of the evening, no damage should occur. Disfiguring of the leaves of the rose bushes is most likely to be due to mildew. Could you please give me some advice on a pond which we have just constructed. Despite all our efforts such as weekly changing the water we have been unable to prevent it from becoming smelly and Sreen. There is a rock garen surrounding it and as yet we have not put any goldfish into it-—“ Ponds" (Ellesmere).

Algae and other minute aquatic plant life can be a cause of annoyance to pond owner*. The use of copper sulphate (blue stone) at the rate of 2>J ounces to 10.000 gallons has been found to be the best means of keeping ponds clear. Fish are unharmed by the copper sulphate and they will also help in keeping the water clear.

I enclose a specimen from a ribbon wood tree. Several of a row are showing these peculiarities. Can you suggest the cause and a cure? “J., Leeston.”

The "peculiarities" are galls that are caused by a fungus. Not very much is known about it, but it would seem to be more prone to attack trees growing in low rainfall areas. The only control that can be suggested is that you cut off the galls and burn them.