YARROW - NUMBERS OF BUDS IN THE SOIL AND THEIR ACTIVITY ON RHIZOME FRAGMENTS OF VARYING LENGTH

Yarrow (A. millefolium L.) plants were established outside, in containers, from rhizome fragments and seed. Relationships between total length of rhizome and numbers of axillary buds predicted bud populations as high as 24,000/m2. In a field experiment, rhizome fragments 4, 8 and 16 cm long were planted at 2.5, 5.0 and 10.0 cm deep. At all depths a greater proportion of the planted buds formed primary regrowth shoots with decreasing length of fragment, e.g., 94, 58 and 53% on 4, 8 and 16 cm fragments, respectively, at 2.5 cm depth. Bud growth appeared to be restricted at greater depths. In another field experiment with 16 cm rhizome fragments planted 15 cm deep, 36% of the planted buds formed primary regrowth shoots. After isolation on single-node rhizome sections, 47% of the remaining dormant buds formed primary regrowth shoots. Suggestions on yarrow control are given based on severe fragmentation of rhizomes by cultivation.