Drought – How are your plants responding?

It’s official: Northern Colorado is experiencing record-breaking drought conditions. An exceptionally warm winter, very little snowfall, followed by a warm, dry spring has the experts agreeing, we are in a drought much like that of 2002. Without the usual spring moisture, the grass simply isn’t growing. One obvious effect on your pastures is that much less forage is available for your grazing animals. After the luxuriously wet springs we had for several years, it is difficult to return to below-average rainfall regime.

Ellen Nelson
Larimer County Weed District

What are your plants doing in response to these drought conditions? All plants are stressed by a lack of moisture; however weeds are always poised to take advantage of reduced vigor in the plants they compete with. Plants under drought stress will have less energy stored in their roots, fewer new shoots, less root mass, and a shorter growth period. Plants that grazing livestock consider delicious will suffer even greater grazing impact during a drought. Non-palatable weedy plants are usually avoided in favor of the more tasty plants.

The way we manage our pastures during drought can make a tremendous difference in which plants come out of the drought in condition to prosper when we finally receive some moisture. The present condition of your pastures is a reflection of how you managed them during the drought years of the early 2000s. We can’t control the amount of rain we receive, but we can manage our pastures so that they are more resilient to the effects of drought and recover more quickly from drought. Good grazing management prior to drought will always lessen the effect of a drought. The healthier your grass, the more leaf and root material produced. Grazing less during a drought leaves more leaf and plant litter present on the soil surface. This litter provides shelter from the baking sun, insulation from extreme summer heat and mulch to help slow evaporation. All of these factors help to lessen the impacts of sun, wind, and erosion.

The most important management decision you can make, especially during drought is when to graze and how long to graze. You look at your pasture and you notice the following: there is less total forage; the grass simply hasn’t grown because of inadequate moisture. You observe that the grass is already stressed by drought; although it’s barely June, the grass looks like it’s beginning to go dormant, the way it often looks in July. You are also aware that without adequate moisture it will take much longer for grass to recover after being grazed. To protect the health of your grasses, and deny the weeds an unfair advantage, you decide to graze your pastures much less than you may have grazed them last year. For a particularly dry area, or a pasture that was heavily grazed last year, you may decide to rest (not graze) that pasture for the entire growing season. If you usually graze a pasture several times during a growing season, you may reduce the number of times that pasture is grazed, and if things continue to be dry throughout the growing season, you may decide not to graze your pastures in the late summer or fall at all, in order to give your pastures an opportunity to re-grow leaf area that was removed by grazing earlier in the year.

Take the time to observe how the weeds are adapting to drought conditions on your land. Remember the weeds are designed to adapt quickly to changes in their environment in order to gain a competitive advantage. While not a scientific study, we have heard anecdotal reports of very different behavior from many weeds this year; we have observed leafy spurge flowering in March when it usually flowers in June. I have noticed extremely vigorous, “beefy-looking” dalmatian toadflax on rocky slopes where the cheatgrass was noticeably absent due to low moisture this spring. It appears that this particular weed is taking full advantage of the decrease in one of its competitors.

Give your plants an advantage in their competition against invasive plants. Provide adequate time for rest and recovery after grazing, especially during a drought.

And remember, in Northern Colorado, we are always looking ahead to the next drought.

The Larimer County Weed District provides advice to landowners on managing noxious weeds. The Weed District provides free site visits, plant identification, advice on controlling noxious weeds and land and pasture management guidelines. Contact the Larimer County Weed District at 970-498-5768 or http://www.larimer.org/weeds/