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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

Weather conditions during June, July and most of August were very suitable for the development and spread of blight. This resulted in the early onset of disease and a rapid development of the epidemic. Most of the initial outbreaks of the disease were recorded in June and were associated with the southern and coastal areas. Later in the season the disease spread inland

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

Annual losses are estimated at 8% (Dowley et al, 1995).

Data for 2002²

Weather conditions in late August and September became very warm and dry. This, together with the use of the tuber resistant cultivar Rooster, resulted in very low levels of tuber blight at harvest.

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

Data for 2002²

Despite the favorable weather conditions, disease control at farm level was excellent irrespective of the fungicide used. Fungicide programmes consisted mainly of phenylamides followed by Shirlan or Shirlan alone and most of the spraying was at 7-day intervals.

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

Decision Support Systems (DSSs), such as SIMPHYT, NegFry, Plant Plus and ProPhy (Dowley, 1997; Dowley et al, 2002; Hansen et al, 2002; Kleinhenz & Jörg, 2000; Leonard , 1999; Leonard et al, 2001) are under validation.

Data for 2002²

The cultivar Rooster, which had tuber resistance to late blight, was grown.

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

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

The A2 mating type frequency decreased from 35% in 1988 to 2.7% in 1996. From 1990 to 1997, the proportion of the Phytophthora infestans population resistant to phenylamide has remained relatively stable (57 % to 38%). This may be due the anti-resistance strategy for phenylamide use (Dowley et al, 1995), which many farmers employ. About 75% of the isolates tested in 1996 (n = 148) had 5 or more virulence factors and 16 physiological races were identified (Griffin et al, 1998).

7. Disease risks and/or major needs?

8. Any publications on late blight in the country?  

Dowley L. 2000. Two decades of phenylamide resistance monitoring. pp 295–296 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.

Dowley L. 1997. Decision support systems for Phytophthora infestans. pp 123–126 in: Bouma E 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, 30 September – 3 October 1996, Lelystad, The Netherlands, PAV-Report no. 1. Applied Research for Arable Farming and Field Production of Vegetables, Lelystad, Netherlands.

Dowley L J, Leonard R, Rice B and Ward S. 2002. Efficacy of the NegFry decision support system in the control of potato late blight in Ireland. pp 81–92 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.

Dowley L J and O’Sullivan E. 1996. The effect of different fungicide treatments on the control of late blight in Ireland. pp 464–465 in: Abstracts of conference papers, posters and demonstratons, 13^th Triennial Conference of the EAPR, 14–19 1996, Veldhoven, The Netherlands. Wageningen.

Dowley L J, Cooke L R and O’Sullivan E. 1995. Development and monitoring of an anti-resistance strategy for phenylamide use against Phytophthora infestans. pp 130–136 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.

Griffin D, O’Sullivan E, Harmey M A and Dowley L J. 1998. Distribution of metalaxyl resistance, mating type and physiological races in Irish populations of Phytophthora infestans: A preliminary report. pp 153–159 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.

Hansen J G, Kleinhenz B, Jörg E, Wander J G N, Spits H G, Dowley L, Rauscher E, Michelante D, Dubois L and Steenblock T. 2002. Results of validation trials of Phytophthora DSSs in Europe, 2001. pp 231–242 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.

Kleinhenz B and Jörg E. 2000. Results of Validation Trials of Phytophthora DSS in Europe in 1999. pp 180–190 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-Special Report no. 6. Applied Research for Arable Farming and Field Production of Vegetables, Lelystad, Netherlands.

Leonard R, Dowley L, Rice B and Ward S. 2001. The use of decision support systems in Ireland for the control of late blight. pp 91–98 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.

Hansen J G, Kleinhenz and Jörg E. 2001. Results of validation trials of Phytophthora DSS in Europe in 2000. pp 23–38 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.

Leonard R. 1999. Further experience with decision support systems for the control of late blight under Irish conditions. pp 81–94 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.

Leonard, R, Dowley L, Rice B and Ward S. 1998. Decision support systems for the control of Phytophthora infestans under Irish conditions – Problems and progress. pp 144–152 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.

9. Is tuber blight an increasing problem?

Yes.

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 Plant Research BV, Wageningen, Netherlands. Information regarding the late blight epidemic in 2002 in Ireland provided by L. Dowley.