Gardeners’ queries

Press, 13 March 1987, Page 8

Gardeners’ queries

GARDENING

by

Mike Lusty

A well established hydrangea suddenly died. Its neighbours, another hydrangea and a fuchsia, are thriving. What could have caused the plant to die and would it be safe to put another hydrangea in the same place? Could you identify a climber I saw recently. It had no visible flowers but a large quantity of small soft indigo berries. It apparently grows quite easily. X.Y.Z. .(Greymouth).

I do not know why your hydrangea has died. They are usually long lived and hardy, provided that they are not attacked by scale insects. As a precaution, remove all remaining vestiges of the dead plant and replace the soil if you are thinking of planting in the same place. The climber referred to could possibly be Billardiera longiflora but it would have been helpful if a sample from the plant had been included.

This climber is in a pot with another plant. Can you enlighten me as to whether it is a plant worth caring for or just a weed? A. T. (Darfield).

The seedling is a passion vine, but at this stage it is not possible to say which one.

Enclosed is a sample from an infested pear tree, and a Coxs Orange apple. The pear tree was grown from seed and is now about twelve

years old. Over the last three years some branches have had their leaves turn black. This year the tree has produced quite a few pears which shrivel up if on an affected branch. All affected branches are removed and burnt. The Cox apple has brown spots through it, and has a rather disappointing flavour and unlike others that I have grown. The trees have been sprayed with insecticides and fungicides. C. J. (Rangiora). Fireblight has manifest itself on this pear tree. Unfortunately, this bacterial disease can become very difficult to control once it has become firmly established. Only the antibiotic streptomycin with or without the addition of terramycin, is effective. All diseased wood should be pruned back to at least 150 mm below the last visible signs of infection. Fireblight is readily spread by tools which have come in contact with it. They should therefore be sterilised after use. All

pruning cuts should be sealed promptly. The apples display symptoms of bitter pit, a calcium related disorder which can significantly reduce the edibility of susceptible varieties, especially in storage. The application of calcium nitrate, from the last week of November, at the rate of 60g/10 litres water, and repeated at fortnightly intervals until harvest, should overcome the problem.

I have two cherry trees about 70 years old. Their branches are dying and one has a hard white fungus like a half tennis ball on its trunk near the ground. I enclose a leaf sample and would appreciate your advice on treatment I have been removing the branches and sealing the wounds. I have also enclosed some leaves of a self-sower native tree which I would like you to identify. S. D. (Chch). The leaf samples failed to indicate any problem(s) associated with the cherry trees. It is possible that silver leal has affected it, as these trees are very susceptible to this disease. When cutting back any limbs on these trees, care should be taken to avoid leaving stubbs. Branches should always be cut off flush with the trunk or junction with another branch. All cul surfaces should be sealed with a suitable sealant preferably one of the proprietary ones containing a fungicide. The leaf samples are from a Hoheria.