606 IOWA DEPARTMENT OF AGRICULTURE 



THE UNDERGROUND STEMS OF QUACK-GRASS. 



The underground stems are the seat of the remarkable vitality of 

 quack-grass, therefore, for a full understanding of this subject the plant 

 in its relations to the underground stems will first be briefly considered. 

 These stems are often called roots. They are not roots in the true sense 

 of the word, but rootstocks, that is, underground stems. The distinction 

 between rootstocks and roots is that rootstocks have buds on them as 

 stems do, while roots do not. Another very important distinction is that 

 rootstocks do not absorb material from the ground, while roots do. The 

 rootstocks are dependent for their growth upon the material absorbed 

 by the roots and elaborated in the leaves in combination with the ma- 

 terial which the leaves draw from the air. This material elaborated in 

 the leaves then goes down to form the underground stems, or rootstocks. 

 The plant is simply storing up material to draw on next year. 



As the material for the growth of rootstocks comes from the leaves, the 

 amount of leaf growth which the plant produces in any one season is 

 largely a measure of the amount of rootstock growth. So, by limiting the 

 development of top in any way the number of underground stems produced 

 is thereby limited. If little or no top is allowed ot grow very little root- 

 stock will be developed. Just as we would expect a small crop of potatoes 

 if we were to keep the top of the potato plant cut back close to the earth, 

 so should we expect a minimum of rootstock growth to be produced by the 

 quack-grass plant if its top is kept closely cut. By actual observations 

 this is found to be true. 



There are three types of management of quack-grass land that bring 

 about three widely different conditions in the vitality of the plant. The 

 three resulting types of quack-grass land are given below: 



TYPES OF QUACK-GRASS LAND. 



(1) A cultivated field infested toith quack-grass. The deepest and 

 most vigorous rootstock development of quackgrass is found in cultivated 

 fields. There are several factors which cause this. The principal one is 

 probably deep preparation of the land. When the plant is left undisturbed 

 the rootstocks have a tendency to get nearer the surface every year. Deep 

 plowing puts the stem back to the bottom of the furrow, and a mass of 

 tangled growth is then sent out toward the surface, a large part of the 

 vitality of the buried stems going into the new stems reaching toward the 

 surface. This new growth lives until the next year. When the stems are 

 buried deeply to begin with and cultivation is not kept up long enough 

 to kill out the grass (and it usually is not on this type of land), the 

 plant takes on a new lease of life after cultivation stops, the loose deep 

 soil furnishing an ideal place in which to grow. As a consequence, the 

 plant becomes firmly established and is well able to stand the next year's 

 battle. 



(2) Meadoivlands. If the meadow has been down for several years, 

 and especially if two cuttings of hay a year have been secured, the root- 

 stock development is found to be about half the extent and depth of that 

 found in cultivated land. 



