Experiment Station Record, Volume 92, January-June, 1945 Page: 52
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52 EXPERIMENT STATION RECORD (Vol. 92
weeds of Iowa, and principles and methods of weed control involving management
and cropping practices, pasturing, burning, and chemicals.
Variations in kinds of weeds from year to year, 0. A. STEVENS (North Dakota
Sta. Bimo. Bul., 6 (1944), No. 6, p. 6).-Russian-thistle, very predominant by
1934, thinned out since 1936 and has not not since become proninent even in the
drier parts of the State. Perennial sowthistle, a menace after the wet year of 1916,
nearly disappeared during the dry period, probable due to drought, weed control,
and grasshoppers, but has been recently reappearing in many places. Marsh yellow
cress (Rorippa palustris) and the docks (Rumex spp.) have shown a direct response
to the wetness of last yeear in the Red River Valley.
Nature and rate of development of root system of Apocynum cannabinum,
J. C. FRAZIER. (Kans. Expt. Sta.). (Bot. Gaz., 105 (1944), No. 4, pp. 463-470
illus. 5).-The root system of well-established dogbane plants consisted of the
original root (primary vertical) and one to many permanent lateral roots which
continued to grow horizontally and on which arose roots either growing downward
directly, or after short horizontal growth, becoming secondary vertical roots.
Plants spread horizontally by means of these permanent lateral roots. Permanent
laterals of the first order arose on the primary vertical root. Branch lateral roots
(second order) arose on the permanent lateral roots of the first order. In a similar
manner permanent lateral roots of the third order arose on those of the second,
and those of the fourth order on those of the third, etc. Injury or too severe
competition was found to prevent extensive lengthwise growth of lateral roots of
any order. Plants spread radially 11.67 ft. and reached a depth of 7 ft. in a
growing season of 28 weeks. Source of shoot development, other than from the
plumule, was from root-borne buds which produced shoots directly (if at the
ground line), or rhizomes (if below ground) which in turn gave rise to leafy
shoots. Shoot development of old plants was wholly from root-borne buds. In
general type of development, dogbane exhibits certain similarities to and certain
differences from field bindweed, hoary cress, and Russian knapweed.
Relation of cultivation to depletion of root reserves in European bindweed at
different soil horizons, A. L. BAKKE, W. G. GAESSLER, L. M. PULTZ, and S. C.
SALMON. (Iowa Expt. Sta. coop. U. S. D. A.). (Jour. Agr. Res. [U. S.], 69
(1944.) No. 4, pp. 137-147, illus. 3).-Effects of cultivation on root quantity and
root reserves (E. S. R., 81, p. 786) in Convolvulus arvensis at different depths in
the soil was studied at Cherokee, Iowa, 1938-40, on heavily infested land. Excavations
5 by 5 ft. were made to 6- to 8-ft. depths three to four times a year. A
high concentration of available carbohydrates (sugars and starch) was present in
the lower soil levels and a concentration of roots in the upper levels, respectively
increasing and decreasing with depth. Cultivation resulted in a gradual and continuous
reduction in the concentration and depletion of the quantity of total available
carbohydrates, a decrease in root quantity, and eventually in death of bindweed
plants. It first affected concentration of carbohydrates, depletion in root
weight being mainly due to loss of carbohydrates. For accuracy the picture of root
reserves in bindweed should include both concentration of carbohydrates and root
quantities in all soil horizons in which appreciable root quantities exist. Since the
greater proportion of roots and available carbohydrates are in the upper layers of
soil, a close approximation may be obtained by sampling the upper 2 ft. only.
See also a previous note (E. S. R., 91, p. 413).
The herbicidal action of 2,4 dichlorophenoxyacetic and 2,4,5 trichlorophenoxyacetic
acid on bindweed, C. L. HAMNER and H. B. TUKEY. (N. Y. State Expt.
Sta.). (Science, 100 (1944), No. 2590, pp. 154-155).-Effects of these chemicals
when sprayed on bindweed (Convolvulus arvensis) and other weeds indicated their
possible values as herbicides.
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U.S. Department of Agriculture. Agricultural Research Administration. Office of Experiment Stations. Experiment Station Record, Volume 92, January-June, 1945, book, 1947; Washington D.C.. (digital.library.unt.edu/ark:/67531/metadc5064/m1/65/: accessed July 27, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.