Cover crops in Black currant

Summary

With the objective to identify the effect of soil cultivation and nitrogen supply in organic production of black currant a field trial was planted autumn 1996 under Unsprayed conditions. The bush rows were cleaned mechanically for weed, and cover crops were established in the alleyways. During establishment all four cover crops gave a sufficient nitrogen supply. The level of nitrogen in soil and the growth were smallest in the annual sown cover crop. Minirhitzotrons were used to follow black currant root growth in total mechanical cleaned plots and plots with sown alleyways. The maximum root dept of black currants of 125 cm were obtained direct under the bush in autumn 1998, whereas the roots only were present down to 40 cm 1.5 meters from the centre of the row. The variety 'Titania' had a deeper root pattern than 'Ben Lomond'. There were no significant yield differences among the soil treatments. There was a tendency to a higher yield for 'Titania' in 2000 in the annual sown cover crop, probably due to the deeper root pattern of 'Titania' and thereby less susceptibility to mechanical root damage. 'Titania' had the highest yield in the two cropping years 1999 and 2000, whereas 'Ben Lomond' had a very low yield due to severe infections of American gooseberry mildew (Sphaerotheca Illors-uvae), which caused very little shoot growth. ' Farleigh ' was susceptible to white pine blister rust (Cronartiunl ribicola) and infections of leaf spot (Gloeosporidie//a ribis) occurred every year. 'Titania' and 'Intercontinental' had the best field resistance to diseases.