Idaho                                                                                Aphid                                                                                                                      Flyer

Green Peach Aphid Alert
    It is time for everybody to get your boots muddy and start turning over potato leaves.
We have not yet seen green peach aphids in our area, but they are defiantly west of us. The usual scenario for these aphids seems to move from west to east. In some areas in Washington they have found 50 to 200 green peach aphids per plant. To check on the aphid counts go to http://www.wsu.edu/~potatoes/jun01.htm or at WSU Hotline for Aphids on Potatoes (888)673-6273. Green peach aphids are pale or bright green and black, with a large, dusky blotch on the dorsum of the abdomen. The immature forms are yellow, pinkish, or pale green. The mature, wingless forms are pale or bright green. These aphids are usually found on the underside of the lower leaves and the wingless forms are about the color of Mt. Dew soda pop. For information on scouting check the University of Idaho IPM program for green peach aphids at  this site; 2001 IPM Program for Green Peach Aphid/Potato Leaf Roll Virus for Pacific Northwest Potatoes
    Alfalfa Aphids-information courtesy of UC Berkley http://www.ipm.ucdavis.edu/PMG/crops-agriculture.html
      The spotted alfalfa aphid is a small, pale yellow or grayish aphid with four to six rows of spined black spots on its back. Mature females may either be wingless or have wings with smoky areas along the veins. New seeding should be monitored closely for these aphids. The threshold for these aphids on new seeding is one per stem. Severe aphid infestations retard growth, reduce yield, and may even kill plants. Damage can also reduce the alfalfa's feed value. A black fungus that grows on the honeydew excreted by the aphid reduces palatability. 
    Aphid counts should be made by carefully cutting a stem close to the ground with a sharp knife, pulling up the cut stem, and then counting the aphids on the undersides of leaves. You can also rap it sharply against a stiff piece of white paper or into a white pan. This will dislodge the aphids and they can be easily counted. This procedure should be repeated, cutting a number of stems at several locations in the field. (While counting aphids, note the presence or absence of lady beetle larvae, parasitized aphid mummies, or aphids killed by fungus.) When inspecting individual stems on new regrowth alfalfa, it is important to pry open small, new leaves and search the spaces between them; many first and second instar nymphs can often be found there. In addition to monitoring aphid populations, also take sweep net samples for lady beetles. 
    For more information and controls see this website; http://scarab.msu.montana.edu/HPIPM/alfalfa_6.htm  

Funded by the University of Idaho Agricultural Experiment Stations and the Wheat & Barley Commissions.

Samples collected June 15 & 22, 2001