THE EFFECT OF WINTER CATCH CROPS ON WEED INFESTATION IN SWEET CORN DEPENDING ON THE WEED CONTROL METHODS

An experiment was carried out in east-central Poland (52 degrees 06' N, 22 degrees 55' E) over 2008-2011 to study the effect of winter catch crops on the weed infestation, number, and fresh matter of weeds in sweet corn (Zea mays L. var. saccharata). The following winter catch crops were grown: hairy vetch (Vicia villosa Roth.), white clover (Trifolium repens L.), winter rye (Secale cereale L.), Italian ryegrass (Lolium multiflorum L.) and winter turnip rape (Brassica rapa var. typica Posp.). The catch crops were sown in early September and incorporated in early May. The effect of the catch crops was compared to the effect of FYM (30 t . ha(-1)) and control without organic manuring (NOM). Three methods of weed control were used: HW -hand weeding, twice during the growing period, GCM - the herbicide Guardian Complete Mix 664 SE, immediately after sowing of corn seeds, Z+T - a mixture of the herbicides Zeagran 340 SE and Titus 25 WG applied at the 3-4-leaf stage of sweet corn growth. Rye and turnip rape catch crops had least weeds in their fresh matter. Sweet corn following winter catch crops was less infested by weeds than corn following farmyard manure and non-manured corn. Least weeds and their lowest weight were found after SC, BRT and VV. LM and BRT reduced weed species numbers compared with FYM and NOM. The greatest weed species diversity, determined at the corn flowering stage, was determined after SC and FYM. The number and weight of weeds were significantly lower when chemically controlled compared with hand weeding. The best results were observed after a post-emergent application of the mixture Z+T. The weed species diversity on Z+T-treated plots was clearly lower compared with GCM and HW.