5.6.2
STROBILURINES IN CEREALS: INTEGRATION IN THE DECISION SUPPORT SYSTEM PRO_PLANT
J FRAHM1, H HANHART1, G KLINGENHAGEN 1, A JOHNEN2 and T VOLK2

1Landwirtschaftskammer Westfalen-Lippe, IPSAB, Nevinghoff 40, 48147 Münster, DE;
2pro_Plant Gesellschaft für Agrar- und Umweltinformatik mbH, Nevinghoff 40, 48147 Münster, DE

Background and objectives
The introduction of this new class of fungicides - Amistar and Juwel - with the active ingredients azoxystrobin and kresoxim-methyl + epoxiconazol has had a major impact on disease control in cereals. To get knowledge on biological principles of this new fungicides, e.g. curative and protective potential in degree-days, uptake and transport of chemical in plants informations from a hundred trials in Westfalen-Lippe over the years 1993-1998 have been collected. The informations extracted have been used for updating the expert system PRO_PLANT, a computer based system using weather data for calculating infection probabilities, crop specific data, amount of disease and variety resistance for timing and rate optimising [1]. The programm is used all over germany and in some other european countries.

Results and conclusions
Azoxystrobin gives excellent protective control on net blotch in barley, glume blotch and tan spot in wheat and rusts in different cereals. The combination of kresoxim-methyl and epoxiconazol gives long term control of the most important diseases with eradicant properties against powdery mildew and impressive curativ activities against rynchosporium, septorias and rusts.

Azoles and morpholines are still very good during active leaf growth, when sprays are applied shortly after infection periods because new leaves emerge continuously and the new growth after spraying is more or less unprotected . An exception is kresoxim methyl against powdery mildew which gives a very good protection in early growth stages. From growth stage 39 on when all leaves have emerged the protective effect of strobilurines proved itself to be the better choice compared to azoles and morpholines.

The trial area is characterized by different growing conditions e.g. wheat is sown from september to december and harvest time from early to mid september depending on year and altitude. The input of high dosages of strobilurines late in season is critical under late ripening conditions due to delayed maturity. Therefore reduced dosages should be applied under specific conditions e.g. in rotations with winter barley after winter wheat or in late ripening conditions.

References
1. Frahm J, Volk T, Johnen A, 1996. Bulletin OEPP/EPPO Bulletin 26, pp. 609-622.