SPECIAL SECTION: 2013 FORAGE GUIDE
Weed Life Cycles
A plant that lives one year or less and reproduces by seeds. Generally annual weeds will be either
considered winter annuals or summer annuals.
Winter annuals germinate in the fall, over winter, then ﬂower, set seed and die the following spring.
Controlling winter annuals should be done in fall prior to the plants over wintering or early in the
spring before the plants start to ﬂower.
Summer annuals germinate in the spring and complete growth by the fall. Controlling summer
annuals should be done in the spring or early summer when the weeds are germinating and are
small. Always try to spray before ﬂowering.
A plant that lives no more than two years and reproduces by seed.
Controlling biennial type of weeds should be done when the plants are germinating or while they
are still in a rosette form prior to rapid stem elongation and ﬂowering.
A perennial type of plant that may live for several years reproducing from seed and or vegetatively
through roots and rhizomes.
Adequately controlling perennial type of weeds is often difﬁcult. The best time to try to control is
when bud stage is initiated and plants start building root reserves. Spraying herbicides that can
translocate to the root reserves will lead to the best control approach. Seedling plants that are in
their ﬁrst year of growth can be sprayed prior to bud stage.
Removal of Plant Nutrients by Forages (lbs. per ton of dry hay)
Cool Season Grass
Warm Season Grass
Grass Pasture (TON)
*Most of the nitrogen is obtained from the atmosphere.
24 WEED LIFE CYCLES