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<br />Emden and Bashford, 1969). Thus, for wheat and perhaps other cereal grains, <br />greenbug infestation potential may increase with less dense plantings. Also <br />water may be manipulated by irrigation or effective cloud-seeding, which may <br />alter herbivore density and thereby reduce plant damage. Chandler et al., <br />(1979) have shown water manipulations to be effective for spider mite control <br />in corn. <br /> <br />Table 1. Greenbug (Schizaphis graminum) density (number per pot) as affected <br />by winter wheat (Triticum aestivum) culm density and date. <br /> Culms per pot <br /> Date Replicate 4 -11.._ ~- ~- <br />7 March 1982 *1 150 77 138 130 <br /> 2 223 154 35 37 <br /> 3 193 199 23 28 <br /> 4 129 86 127 68 <br /> 5 300 -1.ll._ 72 ~ <br /> X 199 139 79 54 <br /> 1 se (30) (25) (23) (21) <br />10 March 1982 .k1 71 96 66 10 <br /> 2 184 107 47 7 <br /> 3 251 234 44 54 <br /> 4 250 134 111 77 <br /> 5 220 JR_ ~. 2 <br /> -- <br /> X 197 144 66 30 <br /> 1 se (34) (24) ( 12) (15) <br />12 April 1982 X 1 1 0 0 <br /> 1 se 0 0 0 0 <br />21 April 1982 X 0 0 0 0 <br /> 1 se 0 0 0 0 <br /> <br />*least squares linear relationship of culm density to insect density: 7 March <br />- Y-intercept = 185.7', slope -3.09, and r2 = 0.84; 10 March - Y-intercept = <br />190.2, slope = -3.68, and r2 = 0.88. <br /> <br />57 <br />