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of the International Hop Growers´ Convention

 

Minutes of the Lecture Part

Scientific Commission of the I.H.G.C., Pulawy, Poland, 27 - 30 July 1999

 

62 scientists from 12 different countries met in Pulawy, Poland, from 27 - 30 July 1999 to discuss latest results in hop research, to exchange experience and to bring home innovative ideas.

30 papers were presented covering the following 4 topics:

 

Session I: HOP Breeding Chairman: Prof. V. Fric

In classical breeding the objectives followed are orientated to meet the demands of the market, of growers and brewer. Main emphasis is put on the aroma and bitter quality with high to very high a -acid contents, low cohumulone content accompanied by high yield and good disease resistance, especially to powdery mildew. Moreover, new selection criteria are highlighted such as dwarfness, resistance to pests, viroid free plant stocks, and compounds such as Xanthohumol, which opens new applications of hops.

 

Session II: NEW METHODS IN HOP RESEARCH Chairmen: Prof. J.M. Jeltsch

Prof. G. Weber

In assessing these selection criteria molecular biology holds great promise. At present great efforts are put into the development of DNA analytical techniques: RAPD, AFLP, and microsatellites are genetic marker systems that are mainly employed to assess the genetic variability in the world’s hop germplasm. Knowledge obtained in those studies can be used for an optimal design in breeding programs. The genetic fingerprint of hop varieties is also used for varietal identification in order to inspect trueness-to-type which is demanded on the market. Moreover, the identification of DNA markers that are linked to important traits is of major importance. First priority is given to the development of DNA markers for disease resistance which e.g. allow to screen for powdery mildew resistance directly at the DNA level.

Molecular techniques are more and more applied in pathogen diagnostic, to proof hop latent viroid, which can be tested for the very first time by using this technique.

Improved in vitro culture conditions have made it possible to improve hops using biotechnological methods. Breeding lines with a simpler genome will increase the efficiency of the breeding procedure by facilitating the selection and combination of valuable traits. Another example is the meristem culture, which is used to eliminate viruses and which is also discussed for eliminating viroids.

Latest studies in Japan and Portugal show that the improvement of hops using gene technology can be realized in the future. These projects are focussed on the genetic manipulation of the a - and ß-acids biosynthesis and on the insertion of virus resistance genes.

The effectiveness of pathogen diagnosis and the "healing" of hops using biotechnology can be seen in the Czech Republic by growing virus-free hops. Virus-free hops show a significant increase in a -acids (40-50%) and in yield.

 

Session III: HOP CHEMISTRY AND QUALITY Chairman: Dr E. Solarska

A min-max model of the gas chromatographical data of the essential oils in hops has been presented, which had been evaluated with various hop varieties in Slovenia for several years. Despite specific uncertainties this model offers a good way to select for fine aroma varieties.

 

Session IV: PEST AND DISEASE MANAGEMENT Chairmen: Mr. J. Vostrel

Prof. B. Javornik

Despite all efforts to breed and cultivate resistant hops it is still necessary to cover production at a very high quality level by applying pesticides. The specific application of highly effective insecticides, acaricides, and fungicides is limited by too few pesticides available. This situation is even aggravated by additional restrictions for hops that should be exported.

An extremely effective way to reduce the application of pesticides is the monitoring system established by Dr Kremheller, Hüll. Comparative studies including two other models proved that combining two systems, one which describes the danger of Peronospora infection by counting zoosporangia and the other which is based on weather data, can reduce the time and labor required for the Peronospora warning system.

In order to reduce the application of pesticides and acaricides, biological plant protection is being exploited. Natural enemies - Typhlodromus pyri and Phytoseiulus against the red spider mite and specific ladybirds against Damson hop aphid - are used as predators. Especially low trellis systems support the establishing of a natural predator population over several years. This biological control in combination with integrated pest management using pesticides that do not harm the beneficial fauna is a promising concept for the future.

All papers presented clearly demonstrated that all hop research institutes and joint universities are working with great commitment and that their results are very promising. The work of the Scientific Commission is the basis for new hop varieties and for an environmental-beneficial and cost-effective production of hops, which increase the international competitiveness of hop growers and brewers.

Dr. Elisabeth Seigner

Secretary, Scientific Commission, I.H.G.C.