By ANGELA O’CALLAHAN
After a relatively wet winter, it should come as no surprise that plants in this region respond to the abundance of water. While temperatures were chilly, they were not terribly cold for an extended period, which would have been a detriment to plants.
Soil moisture permits seeds to swell, something they need to do before germination.
The result of the fall and winter rains can be an explosion of beautiful flowers in the desert. Just as people in other parts of the nation go out to the countryside to see the great fall foliage display, here in the desert, we will often travel to remote areas to see fabulous wild flowers in the spring. Truly, there is nothing like it.
We can conveniently forget that not only lovely flowers produce seeds. In many of our yards and gardens, the additional moisture has given a boost to unwelcome plants. Weeds are opportunists that will appear in abundance when conditions are right.
It can be disconcerting to see green rosettes popping up, unplanned, all over the yard. Many of the earliest plants we see in late winter and early spring are winter annual, or biennial, weeds. With the abundance of rain, we are seeing a healthy flush of green.
Pulling and hoeing are the first lines of attack against these invaders, but that might not be enough when the infestation is large, or the gardener is unable to keep up with weeding. When that is the case, herbicides seem to be welcome tools.
Herbicides (“weed killers”) can be either organic or conventional. Organic does not mean harmless, although these tend to be less hazardous to the environment as a rule.
Many organic herbicides are “burn down”, meaning that they will kill the tissue they touch, but will not be absorbed to kill the plant down to the roots. These are useful for early infestations, while weeds are still small. They do not differentiate between types of plants, so take care not to let them drift onto desirable parts of the landscape. Where weeds have not yet made an appearance, corn gluten meal is an effective preventative.
Conventional herbicides can be selective or non-selective. If a product claims to kill weeds in lawns, then it is designed not to damage grassy plants, but will injure or kill broadleaved ones, such as mustards and thistles. Unfortunately, they can cause problems for vegetables, which are usually broadleaf plants as well.
Anything labeled “weed preventer” either prevents weed seeds from emerging or kills very small seedlings. They are useless when plants have several true leaves.
Some popular herbicides are non-selective. Glyphosate (RoundUp™, for instance) will damage most plants, unless they are resistant. It is essential to apply any of the non-selective compounds following the label exactly to protect gardens from damage.
Do not spray any herbicide when it is warm or windy. Protect yourself from the chemical – it may not be dangerous, but people’s sensitivities vary.
Pulling, hoeing, organic or conventional herbicide, now is the time to get a handle on weeds, before they become garden monsters.
Dr. Angela O’Callaghan is the Social Horticulture Specialist for University of Nevada Cooperative Extension. Contact ocallaghana@unce.unr.edu or 702-257-5581.
