Gardeners’ queries

Press, 13 July 1984, Page 10

Gardeners’ queries

The reply to a query from “Wondering” (Blenheim) relating to the non-flowering of a nerium was missed out last week. It is possible that wrenching of the entire root system may promote flowering. The objective is to shock the plant by severing the roots without cutting the main system. A sharp spade is used tor the job. I have pruned my roses, and would like to know what spray to use now. J.H. (Chch). My preference is for lime sulphur. This provides a very good clean up spray for most problems which prevail at this time of the year. Alternatively, red oil, or any other spraying oil applied at appropriate strength, plus a copper-based material can be used. Thorough coverage almost to the point of run off is desirable. This weed has virtually taken over our lawn and surrounding gardens. We have sprayed and killed the weed, but it is noticeable that it is spreading in directions that missed the spraying. I would

appreciate advice on what action to take to eliminate it from the lawn, and also any suggestions to improve it. S.H. The plant is hydrocotyle, a weed which has become one of the most invasive, and persistent menaces to good lawns almost everywhere, it seems. Control has proved to be very difficult, particularly for home gardeners as the most effective herbicides are not available in small quantities. Other problems are that reasonable control is generally only achieved by repeating the initial treatment at least once. The more established the weed the more tenacious it appears to be. Also, as all the weed killers used on lawns are hormones it means that they are residual. Although grasses are resistant to these herbicides they do absorb the spray. This persistence, which can be variable depending particularly on the strength and frequency of application, precludes the use of clippings for composting or inclusion in the soil

wherever sensitive crops such as beans, tomatoes, and cucurbits are grown. Used with care grasses will not be affected other than some tip burn of brown top, although this grass can suffer from heavy or careless application of several hormones. Currently, the best recommendation for home garden use is the combination of 2,4D/Dicamb, applied when the hydrocotyle is young and actively growing and the soil is moist. Control of established plants may be inadequate. The product combinations of Bromoxynil/Loxynil/Mecocrop, and 2,4-D/Picloram, are more effective but are currently not available in small quantities. Gardeners’ Queries should be sent directly to Mr M. Lusty, 56 Wayside Avenue, Christchurch, 5. Samples should be wrapped separately, in a plastic bag with air holes. Provide a representative, good-sized samples, your name and address, and a non-de-plume if required, for publication;