Weed Variability (March 16, 2016)

Weeds that are the same species can look much different in the field depending upon where and when they are growing. Although the genetic makeup (genotype) of particular weed species are similar, how they look in the field (phenotype) is affected by several factors including exposure to light, moisture, nutrients, temperature, space and other factors. It is not uncommon, for instance, for weeds growing in the dry and hot desert to have a thicker or waxier cuticle to help reduce evapotranspiration and conserve water. It is also common for summer annual weeds to continue to grow through the winter here where winters can be mild and frost-free. They will likely look much different, germinate and grow slower during the winter, however, but they are the same species. This all make identification more difficult especially when using pictures.

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To contact Barry Tickes go to: btickes@ag.arizona.edu.