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1. Late blight occurrence and LB severity by major production area in the country. What crops were affected (tomato, potato, others)? Disease sources (seed, cull piles, volunteer plants, soil)? 

Data for 2002²

LB was not found in early potatoes grown under cover due to dry weather. In open fields blight was first observed on 18 June. The symptoms were on stems. The first blight that originated from oospores was found on 29 June. During the first two weeks of July late blight was reported from all parts of Finland including Lapland where blight is normally not present. The weather was very favorable for blight between 15 June and 15 July. The majority of potatoes in home gardens was destroyed at that time

2. LB impact (foliar damage, yield losses, tuber rot occurrences)?

Data for 2002²

Despite the dry weather, blight was a problem in organic crops. Some fields were heavily attacked early in the growing season. As a whole the situation was better compared to 2001. In many organic fields, late blight can develop freely for long periods. Surveys in 2001 and 2002 showed that in the majority of fields where potatoes are grown organically, oospores are formed.

Farmers started their spray programs in last week of June or first week of July and no large-scale epidemics were reported on these farms. In some individual cases, it was not possible to spray due to the continuous rain and blight lesions were found in these fields. The end of the season from 15 July until harvest was exceptionally dry and warm and the spread of blight was prevented even in fields where blight lesions were found in early July. The dry weather in the later part of the growing season and excellent harvesting conditions resulted in a high quality harvest. 

3. Fungicide use (amounts, types, etc.)?

Data for 2002²

In all parts of Finland the first spray against blight was again earlier than last year. Due to the dry weather at the end of the season spraying in Finland, as a whole, is expected to have been reduced, compared to last year. This probably results in 4-8 sprayings depending on region. For this summer, it was typical that the rainfall and number of sprays varied a lot within regions. In any part of the country within a radius of 20 km there were areas with practically no rain and areas where potato rotted due to too much rain from very heavy local thunderstorms. The most widely used fungicides were Shirlan and Dithane. Acrobat and Tattoo are used to some extent in 1-2 first applications. A very small proportion of the growers used Epok as a first application. As usual, there were reports of failing effects of metalaxyl.

4. Other LB control measures (resistant cultivars, forecast systems, none)?

The NegFry system has been tested, but never used commercially.

Since February 21, 2003, Web-blight, an international web-based information and decision support system for potato late blight is bringing day-to-day information on the first occurrences and the development of late blight in Denmark, Norway, Sweden, Finland, Estonia, Latvia, Lithuania and Poland (http://www.web-blight.net)

5. LB control effectiveness (fungicide or host resistance failures)? 

6. Pathogen strains (mating type, fungicide resistance, virulence factors, etc)?

The A2 mating type was first reported in Finland in 1992. 15% of 200 isolates collected during 1990–1996 were A2. Among the 1834 isolates tested, the frequency of metalaxyl-resistant isolates decreased from 59% (1990–1995) to 2% in 1996. 269 isolates were tested for virulence and all known virulence genes [except R-gene 9, which was not included in the differential set] were detected. Physiological race 1,3,4,10,11 was the most common. (Hermansen et al, 2000).

A study of genetic variability of 141 isolates of P. infestans from Norway and Finland identified 76 mulitlocus genotypes based on mating type and RG57 fingerprints, 53 of which were detected only once. The high genetic distances between them suggest that sexual reproduction contributes substantially to genetic variation. (Bruberg et al, 1999).

7. Disease risks and/or major needs?

8. Any publications on late blight in the country?  

Bruberg M B, Hannukkala A and Hermansen A. 1999. Genetic variability of Phytophthora infestans in Norway and Finland as revealed by mating type and fingerprint probe RG57. Mycological Research 103:1609–1615.

Hansen J G, Lassen P and Röhrig. 2001. Monitoring of potato late blight based on collaborative PC-and Internet applications. pp 39–54 in: Westerdijk K and Schepers H T A M (eds), Proceedings of the Workshop on the European network for development of an Integrated Control Strategy of potato late blight, 6–10 September 2000, Munich, Germany, PAV-Special Report no. 7. Applied Research for Arable Farming and Field Production of Vegetables, Lelystad, Netherlands.

Hannukkala A. 2001. Regional variation in mating type A1/A2 ration, metalaxyl and propamocarb resistance in Finland. pp 215–218 in: Westerdijk K and Schepers H T A M (eds), Proceedings of the Workshop on the European network for development of an Integrated Control Strategy of potato late blight, 6–10 September 2000, Munich, Germany, PAV-Special Report no. 7. Applied Research for Arable Farming and Field Production of Vegetables, Lelystad, Netherlands.

Hannukkala A. 1999. Current status of blight population in Finland preliminary results. pp 183–193 in: Schepers H and Bouma E (eds), Proceedings of the Workshop on the European network for development of an Integrated Control Strategy of potato late blight, 9–13 September 1998, Uppsala, Sweden, PAV-Report no. 5. Applied Research for Arable Farming and Field Production of Vegetables, Lelystad, Netherlands.

Hannukkala A. 1998. Blight forecast and chemical control in Finland. pp 97–103 in: Schepers H and Bouma E (eds), Proceedings of the Workshop on the European network for development of an Integrated Control Strategy of potato late blight, 24–27 September 1997, Carlow Ireland, PAV-Report no. 3. Applied Research for Arable Farming and Field Production of Vegetables, Lelystad, Netherlands.

Hannukkala A, Lehtinen A and Rahkonen. 2003. Observed changes in blight epidemics and their consequences for blight control during the latest decade in Finland. pp 67–72  in: Westerdijk C E and Schepers H T A M (eds), Proceedings of the Seventh Workshop of an European Network for development of an Integrated Control Strategy of potato late blight, 2–6, October 2002 , Pozan, Poland, PPO-Special Report no. 9. Applied Plant Research BV, Wageningen, Netherlands.

Hannukkala A and Lehtinen A. 2002. Development of insensitivity of Phytophthora infestans to metalaxyl and propamocarb hydrochloride in Finland. pp277–278 in: Westerdijk C E and Schepers H T A M (eds), Proceedings of the Sixth Workshop of an European Network for development of an Integrated Control Strategy of potato late blight, 26–30, September 2001 , Edinburgh, Scotland, PPO-Special Report no. 8. Applied Plant Research BV, Wageningen, Netherlands.

Hannukkala A and Rantanen T. 2000. Characteristics of Finish Phytophthora infestans population. pp 262–265 in: Schepers H (ed), Proceedings of the Workshop on the European network for development of an Integrated Control Strategy of potato late blight, 29 September – 2 October 1999, Oostende, Belgium, PAV- Report no. 6. Applied Research for Arable Farming and Field Production of Vegetables, Lelystad, Netherlands.

Hermansen A, Hannukkala A, Naerstad RH, Brurberg MB, 2000. Variation in populations of Phytophthora infestans in Finland and Norway: mating type, metalaxyl resistance and virulence phenotype. Plant Pathology 49:11–22.

Hermansen A, Hannukkala A and Hafskjold R. 1998. Population studies of Phytophthora infestans in Finland and Norway. pp 208–217 in: Schepers H and Bouma E (eds), Proceedings of the Workshop on the European network for development of an Integrated Control Strategy of potato late blight, 24–27 September 1997, Carlow Ireland, PAV-Report no. 3. Applied Research for Arable Farming and Field Production of Vegetables, Lelystad, Netherlands.

Kankila, J.J. Hannukkala, A.O. Rokka, V.M. Pietila, L.T. 1995. Screening Phytophthora infestans populations and breeding for resistance in Finland. pp 261–267 in: Dowley L J, Bannon E, Cooke L R, Keane T and O’Sullivan E (eds), Phytopthora infestans 150, Proceedings of EAPR-Pathology Section, September 1995 Dublin, Ireland. Boole Press, Ltd., Temple Bar in conjunction with Teagasc, Carlow. Ireland.

Lehtinen A, Hannukkala A and Rantanen T. 2002. Infection potential and variation of soil borne Phytophthora infestans. pp 73‑76 in: Westerdijk C E and Schepers H T A M (eds), Proceedings of the Sixth Workshop of an European Network for development of an Integrated Control Strategy of potato late blight, 26–30, September 2001 , Edinburgh, Scotland, PPO-Special Report no. 8. Applied Plant Research BV, Wageningen, Netherlands.

9. Is tuber blight an increasing problem?

Data 2002²

No problems with tuber blight were reported except in home gardens.

Comments, additions and corrections are very welcome. Please contact us at GILB(at)cgiar.org

[2] Schepers, H T A M. 2003. The development and control of Phytophthora infestans in Europe in 2002. pp 9–22 in: Westerdijk C E and Schepers H T A M (eds), Proceedings of the Seventh Workshop of an European Network for development of an Integrated Control Strategy of potato late blight, 2–6, October 2002 , Pozan, Poland, PPO-Special Report no. 9. Applied P.