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2007

Sammendrag

Abstract:  Black cherry aphid [ Myzus cerasi (Fabricius)] and cherry fruit moth [ Argyresthia pruniella (Clerck)] are the main insect pests on sweet cherries in Norway. In this study, application of rapeseed oil alone and rapeseed oil mixed with pesticides were tested as a control method against overwintering eggs of both black cherry aphid and cherry fruit moth. Results showed that rapeseed oil applied at the late dormant stage significantly reduced damage by black cherry aphid. Efficiency of oil mixed with pesticides was higher, but only significant in three of seven trials. The efficiency of rapeseed oil against cherry fruit moth was low compared with what was achieved for black cherry aphid, but within the range that has been reported for other botanical pesticides. As for the black cherry aphid, adding pesticides to oil decreased damage by the cherry fruit moth. Timing of treatment and effect of temperature were discussed.

Sammendrag

Sibirsk Edelgranlus (Aphrastasia pectinatae) er vidt utbredt i Norge. Den kom til Norge i 1960 og finnes nå vest til Seljord og til Bodø i nord. Innen dette området er den til stede, eller potensielt til stede i edelgranplantasjer i et mer eller mindre kontinuerlig belte. Utover dette er den tidligere funnet i Målselv i Troms. Siden 2002 er lusa funnet i bestand av edelgran i Kaupanger og i Luster i Sogn og Fjordane, Ørskog i Møre og Romsdal og Moi i Rogaland. Den til dels kraftige ekspansjonen til områder vest og sørvest i landet er bekymringsfull fordi den smitter lett mellom bestand og den er følgelig nå påvist i det området i Norge som har størst produksjon av juletrær og pyntegrønt. For produsenter av edelgran til juletre og pyntegrønt er Sibirsk Edelgranlus uten tvil den største trusselen mot industrien.

Sammendrag

Combinations of covering and fungicide applications were tested on two sweet cherry cultivars; Van during two years (2001 and 2002) and Lapins three years (2001"2003). The following treatments were tested in 2001 and 2002: (i) covering during flowering and from 5 to 6 weeks prior to harvest and throughout harvest, no fungicides applied, (ii) as (i) but fungicides were applied once or twice between the two covering periods, (iii) covered 5 to 6 weeks prior to harvest and throughout harvest, fungicides applied two or three times prior to covering, and (iv) uncovered throughout the season, fungicides applied two or three times in the period from flowering towards harvest. In 2003, the trees were covered only from 5 to 6 weeks prior to harvest and throughout harvest. Both treatments that year received fungicide applications during flowering, but one of the treatments was left unsprayed during the green fruit period prior to covering. Every combination of covering and fungicide applications reduced total fruit decay at harvest significantly compared to a full fungicide programme and no covering. In three of four trials when the trees were covered during flowering and prior to harvest, and fungicide applications were omitted in the green fruit phase between the covering periods, no significant increase in fruit rot occurred compared to treatments where fungicides were applied. However, in one trial there was a significant increase in fruit rot by leaving out one fungicide spray during that intermittent period. Furthermore, if fungicides were only applied during flowering and not on green fruit before covering in 2003, a significant increase in fruit rot occurred. Thus, leaving out fungicide applications during that supposedly less susceptible green fruit period, increased the risk of acquiring fruit rot. Applying fungicides during the green fruit stage significantly reduced the amount of brown rot in four of five trials and anthracnose in one of five trials. No negative effect on fruit quality was found from the extended covering periods. It can be concluded that covering effectively replaced fungicide applications during flowering and prior to harvest.

Sammendrag

This Pest Risk Assessment (PRA) of the fire blight bacterium Erwinia amylovora was initiated by a review or revision of a policy by the Norwegian Food Safety Authority. Fire blight was detected in Norway for the first time in 1986. The focus of infection was in and around the city of Stavanger in Rogaland county on the south west coast of the country. Mainly Cotoneaster bullatus and C. salicifolius were attacked.  The disease was contained and finally eradicated from the area in 1992. However, in 2000 fire blight re-emerged, in the same county, on the island Karmøy, separated from the first outbreak by 25 km open sea. A new containment and eradication programme was started. Nevertheless the disease continued to spread to the north, mainly due to the movement of beehives contaminated with E. amylovora, from areas with diseased plants to areas free from fire blight with warm and humid weather conditions, favorable for the development of the disease. Fire blight has been detected in private gardens, around public buildings, in recreation grounds, along roads, and in rural areas in the coastal areas of the counties of Rogaland, Hordaland and Sogn og Fjordane. It has not been detected in nurseries, in fruit-growing areas, or in other parts of the country. The main hosts are still C. bullatus and C. salicifolius and some other Cotoneaster spp. Occasionally diseased Sorbus aria, Pyrachanta and apple and pear have been detected. Recently a very limited outbreak on C. bullatus and C. salicifolius was detected in the city of Kristiansand in Vest-Agder county. The endangered area, where presence of fire blight will result in economically important loss is the commercial fruit growing areas of Norway. If E. amylovora is introduced into the main fruit growing districts, it is expected that the damage and losses to commercial fruit production and nurseries will be minor, under the current phytosanitary regime in Norway. Relaxation of the regulations in force for fighting fire blight in Norway will increase the expected damage and losses to commercial fruit production and nurseries to a moderate level. Importation of fruit trees and fruit tree propagation material from countries where fire blight is established is not expected to increase the risk of fire blight in Norway significantly, given that appropriate phytosanitary requirements and quarantine are followed.

Sammendrag

A series of field trials combining cultivars with different levels of resistance to Phythophtora infestans and different haulm killing methods was conducted in 1997, 1998 and 1999 to assess the contamination potential of the haulm. In addition, the frequency of tubers with late blight was assessed after harvest and storage, combining effects of pretreatment infection, infection by the haulm at harvest and the development of the disease during storage. Haulm killing was performed by diquat (200, 400, 600 g a.i. ha-1), half cutting of the haulm in combination with diquat (100, 200, 300 g a.i. ha-1) or full cutting of the haulm. In those treatments where haulm killing was performed purely chemically the haulm remnants" contamination potential tended to increase at reduced doses. Full mechanical destruction gave as low a contamination potential as application of the full dose of chemical haulm killer. However, there were no consistent differences between the haulm killing treatments in the frequency of blighted tubers after harvest and storage. This indicates that the input of chemical haulm killers may be reduced. There was a large difference between years in tuber blight after harvest and storage, which confirms that climatic factors are of major importance for tuber infection. The large difference found between the cultivars in the frequency of tuber blight indicates that tuber resistance should be an important part of integrated late blight disease management.