Gardeners' Queries...

Press, Volume C, Issue 29625, 22 September 1961, Page 6

Gardeners ' Queries...

Coald bonemeal or bone flour be substituted tor superphosphate in the fertiliser mixtures recently recommended by you? I believe that super burns up the humus in the soil; I know it certainly rots the baft it is packed in. (F.M, Motueka.)

Both these materials may be used as alternatives for superphosphate if desired. They contain a slightly higher phosphate content and also certain quantities of nitrogen, so that there is no need to use them at higher rates. However, their cost in terms of P 205 content is rather higher than super. It is an oftrepeated fallacy that super burns up the humus in the soil. This is not so. What frequently happens with super is that it enters into a combination stage in the soil in which it is “fixed” or unavailable to plants. I enclose wallflower plants for examination which have a browning of the leaf tips. They were planted on soil dressed with Phytazol S and then topdressed with fresh soil Sin deep. The treatment was carried out in December, and only the wallflowers have been affected from die lange of flowers planted, including Iceland poppy and pansy We have had a very wet winter. Can you suggest the cause? (G.8.R., Waimate.)

I have no doubt that the damage is caused by the Phytazol S. This material is very persistent in the soil—that is its virtue as a weedkiller—and Phytazol S is even more persistent than Phytazol C. It acts both as a foliage and rootkiller. The wallflower is probably more susceptible to the residue in the soil, or has penetrated more deeply into the soil, which is why it alone is showing symptoms. The wet winter, too. would encourage the movement of weedkiller in the soil, although it is stated to have a slow lateral movement. I cannot offer you any way out of the difficulty, short of waiting. The persistence is regarded as being about two years My camellia has had two moves in the last season whilst we were building. It was healthy last autumn, but now looks sick. It has had blood and bone. I enclose specimens. (S.T., Fendalton.)

The constant moving of plants cannot be too strongly deprecated, and this accounts for the poor colour of the foliage. You give me no details about the blood and bone ap-plication-rate or time. You do not get an immediate reaction. You also have an attack of tortrix moth on the foliage, which causes the brown, chewed areas where the surface tissue Is lacking. This would have been caused last spring, although you may not have noticed it before. Keep a close watch this spring, when the new leaves are unfolding. You can spray with D.D.D. (not D D T ). or preferably pinch the leaves together when they are seen to be webbed to each other—the caterpillar will be between.

I cannot help you with your conifer trouble. I’m afraid your description is not thorough enough, and the samples show symptoms which could be due to several dissimilar causes.