EFFECT OF VIRUS AND MYCOPLASMA DISEASES ON PRODUCTIVITY OF ALFALFA HAY CULTIVARS

Abstract

Purpose: To evaluate the productivity of different alfalfa hay cultivars under the effect of local virus and mycoplasma diseases. Methodology: The study was conducted under center pivot irrigation system similar to TADCO mechanized alfalfa hay crop production. Results: Imported alfalfa hay cultivars were found infected with three virus and mycoplasma diseases: alfalfa enation virus, alfalfa mosaic virus and alfalfa witches' broom. Infections with these diseases lead to a severe reduction on the productivity of alfalfa hay cultivars in the third cropping season. Alfalfa enation virus was found to cause the most economic damage to the alfalfa hay crop, and the percentage yield reduction from this disease reached 17.6, 36.8% in the second and third seasons of cultivation respectively. Unique Contribution to Theory, Practice and Policy: The authors recommended to grow alfalfa hay cultivars with less susceptibility to virus diseases infections as we found variability in the productivity of the tested cultivars. The study also recommends to grow alfalfa hay cultivars under mechanized system for two seasons as we observed significant yield reduction in the third season due to high infestation with weeds and grasses which affected the hay quality. In the first field trial (1999 - 2002), productivity of alfalfa hay cultivars CUF 101 and Siriver reached above 30 M.T. /Ha under aphid-controlled conditions. In the second field trial (2002 - 2004), alfalfa hay productivity of the cultivars Fast Grow, SW 9500, Magic (SW 9301) and Super Supreme reached above 30 M.T./Ha in the first season 2003; and in the second season 2004, productivity of Magic, Fast Grow and Super Supreme reached above 26 M.T./Ha. Productivity over the two seasons 2003 and 2004 shown Fast Grow and Magic were the highest with 60.38, 59.85 M.T./Ha. respectively.