Effect of soil cover on weeds

The influence of depth of soil cover and particle size on weed regrowth were evaluated. White mustard (Sinapis alba L.) and scentless mayweed (Matricaria inodora L.) seedlings at different developmental stages were used as test plants in outdoor pot experiments where the influence of depth of soil cover and bending the plants prior to covering was investigated. The plants had to be at least totally buried to be significantly controlled, so taller plants needed a thicker soil cover than shorter ones. The effect of covering was greater if the plants were bent before treatment. The influence of covering with sand of various particle size was investigated in indoor experiments. Annual bluegrass (Poa annua L.), lambsquaters (Chenopodium album L.) and scentless mayweed (Matricaria inodora L.) seedlings were used as test plants. The effect was greater after covering with sand of small particle size than when larger particles were used. When the upright growing plants were bent, the thickness of sand needed for effective control was less than 1 cm when sand with a particle size of 0.10 mm was used whereas a depth of 1.5 cm was needed for a particle size of 0.95 mm.