NOXIOUS WEED RESEARCH

Nelson Evening Mail, Volume LXIII, 1 April 1929, Page 2

NOXIOUS WEED RESEARCH

PROGRESS OF THE WORK ! At tne lasi, meeting of the Noxious Weeds Research Committee., presided ever by Professor 11. !'•• Kirk (and' briefly 'reported last week), \h- 1). Miller stated that a full scheme of cooperation with the parasite zoo established by the Empire Marketing Board at Farnliiim Royal, England, had been arranged. Consignments of insects to ottack gorse, ragwort, blackberry and other weeds had been regularly received from Faruhain Royal. A scheme of Forest Biological Research had been prepared and was now receiving consideration by the (.lovc.rument. flte object of this scheme was to provide an adequate means for the protection of tire 'Dominion's native forests and plantations against loss through the ravages of insects and fungi. The estimated expenditure for the coining year was considered and approved. 'The cost of the investigations lire shared by the Empire Marketing Hoard, Cawthron Institute and the Department of Scientific and Industrial Research. £3OOO is being expended upon the New Zealand investigations and £IOOO in England. THE TYRTA MOTH The Tyria moth, which has been libcrated in ragwort infested areas tit Te Puke, Stratford, Nelson and Southland was establishing itself well. Particularly favourable reports had been, received 'mm Taranaki. Altogether some half a million eggs had been distributed. If was too early yet, to estimate the success that was likely to at!end the liberation of these ragwort destroying insects. This year's trials would, however, provide valuable information in respect to its capacity for enduring the New Zealand winter and the degree to which it wis likely to lie attacked by parasites. Steps were being taken in some of the infested areas io arrange for the transference of the insect, to ither arc.-i> in fhe immediate v'cinity. If successful, it was hoped to have greatly increased numbers .of eggs available next year for widespread distribution throughout all ragwort infested areas of the Dominion. BLACKBERRY PARASITE In. the trials conducted with the blackberry parasite, Coroebus, at Nelson, great difficulty had been oxperienc ed in getting this insect to breed properly in the large insectary. This insect's natural habitat was the hot, dry, sunny Mediterranean shore line of Southern France and as it appeared that conditions in the large insectary were too -:ool to permit its best development, it had become necessary to use artificial heat and light with those insects which had established themselves in blackberry roofs so far. In .lonsr-ruience small numbers only were available for experimentation, ami as yet it had not been found possible to try out Coroebus on any but it small range of economic plants. Tn the adult stage the insect had attacked leaves of raspberries. The insect's destructive work,

however, was carried out in the larval stage when it attacked" blackberry stems boring spiral tunnels downwards towards llio roots. THE GORSE INSECT The gorse insect, Apion ulie.'s, had shown a remarkuble loss of fertility wjio.ri liropqrtcd to New Zealand. Out of 38,000 pupao already imported sumo 16,000 insects had emerged, bid, from these the Now Zealand progeny had amounted to only 125 'lbis shewed ihe difficulty that had been experienced in acclimatising the insect m New Zealand. Gas analyses of the containing boxes wore being, made on arrival in Now Zealand in an endeavour to ascertain if the amount of carbon dioxide present had exerted any influence upon the virility of both Apion and Tyria. More hopeful results were being obtained from the sub-station established recently on Fluff Staff Hill, Dunedin. Some 3,000 A pious were being tried out there and egg-laying was now proceeding in. some 50 per cent of the gorse pods in the specially enclosed insoctaries. From sample tests made recently it would appear that the fertility of the females was increasing and had increased from 60 to 80 per cent between two inspections. It was decided to continue these tests and to conduct trials with the insect upon all economic plants likely to he attacked before any decision to release was made. The singular difficulties attaching to the acclimatisation of Apion were exceedingly puzzling. Work was still proceeding in connection with Piri Pin and foxglove parasite but no new developments had been recorded.