Further studies on the use of fungicides for control of chalkbrood of the alfalfa leafcutting bee

Results of this and other studies indicated that frequent dusting of nesting units of the alfalfa leafcutting bee with the common fungicide captan significantly reduced the incidence of chalkbrood. Treatments with another fungicide, benomyl, were less effective in disease control. Applications of either fungicide did not appear to adversely influence mortality of larval stages and/or adults of leafcutting bees. Some disruption of nest-recognition cues may have occurred since greater percentages of cells were lost to nest supersedure and unfinished cells were found in treated nests. As two methods of cell analysis produced different estimates of mortality factors, a need to standardize sampling procedures is indicated.