Plant health monitor

Press, 5 March 1982, Page 21

Plant health monitor

Information

Drought- conditions are still uppermost in most farmers’ minds, so it may be some consolation that problems caused by plant pathogens are unlikely at this time of year.

body or are honey coloured around the midsection. These bacteria can cause up to 80 to 90 •per cent mortality. Grubs attacked by fungi will have obvious symptoms. Diseased specimens should be sent in a sealed container, such as a matchbox wrapped in foil. LUCERNE • Feeding lucerne hay to sheep already grazing on lucerne, can introduce or spread stem nematode within a stand. Even hay grown “on farm” may be a source of infestation. Do not feed hay on any paddock destined to be drilled into lucerne this autumn. • Autumn growth of lucerne can be infected by leaf spots which increase the phyto-oestrogen levels in the plant. These chemicals can suppress ovulation and reduce lambing percentages in ewes flushed on lucerne. In practice combine the feeding of pasture with lucerne. STOKE GRAIN © Some cereals have now been stored for longer

On the horticultural scene the harvesting of many crops is either just completed or in full swing. Previous poor mangement and inadequate chemical control are showing up through poorer yields. PASTURE • A large flight of Tasmanian grass grub beetle occurred last week-end. In some localities literally bucketfuls of these black elongated beetles were collected. Recent sampling has already indicated small black headed first stage grubs. Note the date of any future flights and be prepared to sample for this pest over the next one or two months. Where control is necessary use Fenitrothion at 1 kg active ingredient per ha. • Continue to sample for grassgrub and porina. e The Insect Control Section of MAF, at Lincoln College, would appreciate receiving any apparently diseased grass grub. Grubs suffering from bacterial attack lack the distinctive black strip through the middle of the

than a month and should be checked. If the temperature at the centre of the silo is over 21 degrees C, sample for insects or mites, (see AglinkFpp2oo). POTATOES • Dry rot of seed potatoes is more common in dry seasons. Seed growers should consider applying the fungicide Thiabendazole during harvest or prior to storage. BERRYFRUIT and ORCHARD CROPS • Mites continue to be a severe problem. A clean up spray after harvest may help to prevent future problems. CARROTS © Carrot rust fly and aphids could be a problem. To reduce the risk of aphid infestation sow as late as possible in the autumn. For carrot rust fly apply phorate granules, preplant at a high rate in soils with a high organic matter content, e.g.: peat. Diazinon pre-plant on medium soils, or fensulfothion and disulfoton (two chemicals with tentative label claims) can also be used.