Gardeners' Queries

Press, Volume C, Issue 29673, 17 November 1961, Page 8

Gardeners ' Queries

I enclose a leaf of notyanthus. Haats have produced Suite sizeable blooms, Out bath polyanthus and hydrangeas tn the same garden suffer from an acute yellowing of the leaves at that on the specimen. Could yon advise on the cause and the remedy? (BJ., Geraldine.) Your polyanthus is suffering from iron deficiency. The leaf began to regain its normal green colour when kept for several days in a solution of an iron salt. Iron deficiency normally results from soil conditions which supply too much lime. The time inhibits the uptake of iron, and leaf yellowing results. Some land around Geraldine is somewhat limy, but it may be that an excess of lime has been applied to the garden in the past. Since iron salt applied to limy soil is immobilised, it is not possible to remedy a deficiency directly. Instead, the required iron is applied as a spray, preferably ferrous sulphate, at between 0.2 and 1 per cent, solution. This spray is applied to the foliage before It becomes too mature. It is also possible to make the soil more acid by applying sulphate of ammonia or sulphur, and thus render the iron in the soil available to plants. My Burbank plum has had a heavy crop of fruit this year, but there are numerous peculiar flattened fruits amongst those set. A sample is enclosed. Could you tell me what they are and whether they should bo removed from the tree? I have had this tree for about 10 years but this Is the first time it has happened (A.A., Reeftea.) This trouble is a disease caused by a fungus allied to peach leaf curl, and deformed fruits are known as plum "pockets." Unfortunately, the only means of control is the removal of infected fruits and the shoots which bear them, removing the source of infection for future years. In your case this is not a very practical solution, since affected and unaffected fruits occur together, but there is not an effective chemical control. 1 enclose specimens of raspberry which show signs of trouble. Most of my canes seem to have died baek, as they are producing no leaves from the tips, although new canes are springing from the base. The young leaves of some plants are full of small holes, although I cannot find any insects on the job. Some of the leaves are affected by a yellow spotted fungus. (K., Timaru.) The raspberry canes have been attacked by the raspberry bud moth. This has small caterpillars which bore into the buds and destroy them before they break into growth. If you open a bud which has not broken you will find that it Is empty, with no growth point. They may also burrow into the pith of the shoot and attack the buds from within. Control is by means of lead arsenate sprays, which will also control the pest causing the leaf holes —bronze bettie. Raspberry moth has about four generations a year, so that repeated sprays are needed, using arsenate at •ioz per gallon of water, in September October, early November, February (after the fruit is picked) and at leaf fall. Prune the bushes as early in autumn as possible and destroy the prunings. This will reduce the liability of infection. The

leaf fungus is rust—Me the answer to E.M.S. above. I regret that the specimens of strawberry and tomato had deteriorated In the post and Identification was not possible. I enclose a leaf from my Azalea Indies “Phoebus.'* which is swollen and distorted, with a white meally surface. Last year I had other leaves affected in the same way, but this la the only leaf affected so far this year. Could yon advise of the trouble and remedy If needed. (BM W., Papanut) The azalea is affected by azalea leaf gall, which only normally attacks evergreen azaleas of this type, and under humid conditions. It is common where azaleas are grown in glasshouses for decoration. Control measures are not warranted in this case. Just remove and destroy infected leaves. Please send your plant for identification when in Bower. Your other queries will be answered later. 1 ’enclose a sample of raspberry leaves, which are affected with bright orangyyellew spots. This trouble is fairly widespread over the plants, although they appear to be healthy otherwise. Could you please tell me what it is and what to do about it? (E.M.S., Raagitata.) The trouble is raspberry rust, a fungus disease which has spread considerably since it was first observed in the North Island in 1945 Although the attack does not appear severe at the moment, it can cause quite bad defoliation. Since the fungus persists over the winter In dead leaves, these chould be gathered and destroyed. A sulphur spray in spring when new canes are six to 12 inches tall will avoid re-infection, or sulphur dusts would probably be easier to apply. If you wish to use a spray, then the following formula may be used next spring: 3 fl. oz of lime sulphur. 1 fl. oz of colloidal sulphur, end 4 gallons ot water. Alternatively. the much stronger spray of IV, pints of lime sulphur in 4 gallons of water may be applied in the autumn when leaves start to fall. Do not apply this spray now or you will strip all the leaves off the plant. Could you tell me why the stems of Iceland poppy go crooked? I have a row which have straight stems until they are almost ready to bloom, and then they grow as crooked as a figure 8. They are healthy plants and are not growing close to anything that would overcrowd them. (Mrs C.F., Reefton.) Iceland poppies always seem to have a slight tendency to wiggly stems just under the bud. but not as severe as you describe. Have you been spraying with hormone weed-killers nearby? They cause contortions like this. The cause,, for the naturally wiggly stems Is probably due to unequal growth rate on opposite sides of the stem, resulting from wind, sun, and other factors when affecting the plant unevenly.