Two nitrogen fertilizer compounds (ammonium nitrate and urea) were
applied al 3 rates each to wheat plants cultivated during 1992/93 in the
Experimental Farm of the Faculty of Agriculture at Moshiohor. Aphids
population started low and increased gradualh until reached the highest peak of
abundance at the end of March.
Infestation rates with aphids increased under all treatments with N
fertilizers. Urea application ai the rate of 120 kg/fed, was found associated with
increasing numbers of aphids on wheat plants. Aphids disappeared on wheat
plants during the last week of April. Appearance of bioenemies was observed in
the second half of February and reached their high peak in the end of April.
Seasonal mean in numbers of bioenemies/ 100 plants was highest in the urea
treatment at the rate of 120 kg/fed.
The grain yield increased in all nitrogen fertilizer treatments compared
with control. The grain yield and 1000 grain weight increased as the rate of
applied fertilizers increased up to 90 kg/fed. for the two compounds.