Soybean
Aphids are Starting to Colonize Soybeans
Scouting efforts on June 6, 2008 found a low incidence of aphids in one
field (3 aphids on one plant in 100 examined). This field in Arva was planted
early and has reached the first trifoliate stage. Scouting of other fields in
the area did not detect the presence of soybean aphids in any other fields. Overall
the incidence of soybean aphids to date is low in Ontario but early planted fields
should be scouting in the next few weeks to ensure that SBA populations do not
increase in these fields. The field found today in Arva was directly across from
a plot that last year was colonized with SBA by May 10th and was sprayed by June
11th last year because the aphid population had reached threshold. The observations
made today indicate that we are no where close to what we experienced last year
but is more typical of a normal year when populations are noticed on soybeans
near second week of June (9th -14th) time period. The most likely source for these
aphids is from buckthorn in the area (local) and not dispersal from distant locations
(wind). Michigan State University (Chris DiFonzo) has also found a site with soybean
aphids on plants but the Michigan site has a much higher incidence (60% of plant
infested with soybean aphids).
