Garden queries

Press, 4 March 1988, Page 16

Garden queries

GARDENING

by

Mike Lusty

In trying to make up the problem of a very poor soil — a very messy dug created by contractors — I have incorporated pea straw, lime, and horse manure. According to the experts I have only succeeded in introducing wireworm, which I presume were responsible for the tunnels in the enclosed potatoes. However, recent nocturnal inspection revealed dozens of slugs and it occurred to me that they could be the cause of our losing most of our potatoes for the last few years, .and also contributing to (the smelly mess they are) in. Blitzem, D.D.T m and sulphate of ammonia have been used to combat them. W.M. (Ashburton).

The information provided in this query calls for several observations. Potatoes I require an acid soil and do not thrive in alkaline, poorly drained mediums, or those subject to waterlogging. [ The addition of organic matter and animal manures is recommended but it should not be fresh, and is best incorporated at least six to eight weeks before planting. Wireworms, the larvae of the click beetle, are a pest of potatoes as well as numerous other plants, and will; bore into the tubers at all stages of development. They make very smooth rimmed holes, and may tunnel extensively. Slugs (and other insects) use and frequently enlarge j these burrowings. The damage also invites the development of fungal infections. However, the presence of early blight,, which is responsible for the; very repugnant smell and rotting of these tubers, was fostered by prevailing weather. Although wireworms

are said to be accentuated when pasture is turned in there is no real evidence to show that this, or the addition of any other matter to the soil, particularly influences their presence. Lindane and D.D.T. were once recommended for the control of wireworm, but their use can also taint the tubers if used excessively. Baits such as hollowed out bits of potato placed just below the soil surface can be used to trap them. Blights can be very prevalent under warm, damp, and humid conditions and timely applications : of a copper-based preparation, maneb, or chlorothalonil will provide control but will not stop infection once it has established itself — that is why timing is so important.

Some pests seem to have been laying eggs on the back of the enclosed gerbera leaves. It makes them look like the face of that man in “The Singing Detective.” I tried spraying with summer oil, but It had no effect. Could you please identify the pest and suggest treatment. Bryndwr. ; . White rust of gerbera/ is not infrequently mistaken for a plague of insects. This fungal manifestation can be most debilitating. Fewer and smaller flowers are produced, and there is a general loss of vigour of the plant. Control becomes difficult once it has established itself, and some gardeners go so far as to advocate uprooting and destroying the infected plants. Double the recommended strength of either maneb or zineb applied frequently and thoroughly is reasonably effective when applied as soon as the disease is noticed.

We have a property in Akaroa from which the following observations have been made. Two hazel nut trees bore a small crop of nuts last year, but this year the kernels were either powder or shrivelled up. I did notice that ail the leaves on the south-west side were

burned and spotted. It was noticeable that many other trees were also affected. This prompted me to go for a walk in the south-west of Akaroa and I noticed the burning of tree leaves got worse. My conclusion was that this was caused by spray damage. W.P. (Chch).

i Strong, salt-laden winds recently swept much of the Peninsula coast, line, and this was particularly noticeable in the Akaroa area. Winds of this nature can cause considerable damage to even the most acclimatised trees and shrubs although it may be only superficial, varying from marginal scorch to complete browning and withering of leaves and soft new growth. This would link up with the observations outlined in this query, and what was noted of the condition of the examined hazel nut foliage. The nuts suggested the possibility of insufficient pollination, a vital factor in successful qualityproduction. It is recommended that suitable pollinators be planted on the windward side. It should also be noted that hazel nuts are averse to hot dry winds through the summer, and also to drying out over the same period.

I have the enclosed weed growing in my lawn and would like to know how to get rid of it. “Senior Ciizen” (Ashburton). The control of clovers in lawns is not always achieved with one application of herbicide, especially if a wetting agent is not included. The combination of dicamba and 2,4-D is recommended for this job.

, Gardeners’ Queries should be sent directly to Mr Mike Lusty, 56 Wayside Avenue. Christchurch 5. Samples should be separately wrapped in a plastic bag with air holes. Provide representative, good-sized samples, and your name and address. A nom-de-plume can be used for publication.