Identifying Coreopsis Pests and Diseases
Coreopsis, also called tickseed or calliopsis, is an herb that is native to North and South America. Coreopsis usually produce yellow flowers that look much like daisies, with teethed edges. Coreopsis are known for their simple maintenance and ability to thrive in most any location. They are practically drought resistant. Coreopsis look beautiful in all seasons, as during winter, they turn a cinnamon brown. Although they are very hearty plants, they are still susceptible to pests and disease especially when not properly maintained or if they are damaged. One key note to remember is that a little plant care such as proper watering and fertilizing, can build your Coreopsis' strength to fight off both infestations of insects and infections. Sometimes, though, no matter what you do, your plant will acquire some kind of problem.
Both of these symptoms point to the strikingly odd disease, Aster Yellows. It won't cause the flower discoloration like a fungus or bacteria would, meaning there would be no brown or necrosis (at first). What you may notice is the loss of pigment in the flowers, making the flowers turn the green of the rest of the plant. You may also notice strange deformations that look like another little, bushy plant growing off of yours. With both of these symptoms, Aster Yellows is highly probable. There is no cure to rid the plant of this bacteria. However, a good way to prevent the disease is to take preventative measures against the next common problem of coreopsis-the Aster Leafhopper.
Yellowing along Tips of Leaves
Since the Aster Leafhopper pierces the leaf and injects a toxin, this area becomes noticeably yellow, both on the peripheries of the leaf as well as small spots around the interior of the leaf. This is the pest that spreads the Aster Yellows disease and it is important to protect against them, but if you haven't pre-treated your plants, you still have options. An insecticide specifically for Aster Leafhoppers should do a world of good. If you do make it to the point of having Aster Yellows, this may also prevent more damage from being done to your plant by continued infestations.
Leaf Texture/Color Changes
If you notice a little discoloration associated with a different texture in the same area, you may be looking at a fungal infection. This can look like powder or little hairs, and it will generally discolor the area of the leaf to a yellow or brown, or sometimes make the leaf very dry. Fungicides specified for your coreopsis will show almost immediate results. Remove leaves that have been extensively damaged.
Mottled leaves are usually signs of a mosaic virus. If you notice this, immediately take a leaf sample to your local extension educator for analysis. If it is a mosaic virus, it is important to remove the plants without damaging them (it is through their fluids that these viruses are often passed). After removing destroying them, sanitize the soil before planting anything else in the same place. Keep a very close eye on surrounding plants for signs of the virus.