|
|
|
Weeds
Volume 52 Number 14 Date 07/13/2007 Roadside weeds - Wild parsnip is forming seed in Columbia and Dodge counties, while spotted knapweed and wild carrot are near or just past full bloom. Both wild parsnip and spotted knapweed are extremely invasive plants that tend to create monocultures in areas where they grow. Clipping and bagging flower heads now will help to slow their spread and keep populations in check. CAUTION! Be sure to wear gloves, long sleeves and other protective gear when controlling wild parsnip. The plant sap is very phototoxic and will burn skin. Weeds in corn - Redroot pigweed (Amaranthus retroflexus), a common problem weed, was observed in scattered Dodge County corn fields this week. Amaranthus retroflexus is a summer annual capable of prolific seed production and triggering late summer allergies. Interestingly, Native Americans used to collect the plentiful seeds to ground into flour. Pigweed species can be difficult to distinguish from one another, especially since hybridization is common. Leaves on redroot pigweed are characterized as alternate, simple, lancelate to obovate in shape, with prominent veins. The taproot is relatively shallow in the ground and upper portions are red to pinkish in color. At this point in the season, weed control in corn is complicated by plant height and developmental stage. In the more advanced fields, weeds left unchecked may have already caused yield loss, and applying an herbicide is no longer economical. Some later fields may still be at a stage where control is economical; assessments should be made on a field by field basis. Record observations on problem weed species now to create a targeted weed management plan for next year. --Clarissa Hammond 
|
|