Chrysanthemums & Pests
- Thrips aren't too bad but may cause chrysanthemums some problems if they're grown in a greenhouse or any hot, dry climate. This type of pest discolors and shrivels the buds and blooms.
Fumigating the plants with insecticide should keep thrips under control, or you can regularly spray with insecticide if your chrysanthemums are growing out in the open. - Aphids that chrysanthemums attract are brown or black, and they feed off of the plant's sap by piercing the tissue and leaving honeydew behind. They particularly like areas showing new growth: leaf undersides, buds and shoots.
Symptoms include stunted or distorted growth and can lead to the death of chrysanthemums. To get rid of them, you'll need to forcefully spray the plants, especially the leaf undersides, with water every couple of days for at least a week. - Small, dark, female adult flies lay eggs (larvae) on the undersides of leaves. They pierce the leaf surface when they hatch, feeding and living inside. These leaf miners leave behind pale green or brown trails (with the occasional black dot of excrement) when they move through the leaf.
If chrysanthemum leaves droop down or dry up, it could be a sign of a leaf miner problem. Eliminate any infested leaves that are still on the plants or that have fallen off. Remove any dead plant parts when autumn approaches, or you can spray with an insecticide for leaves if the damage is great. - Be more aware of these pests if you live in a hot, dry area. Have a magnifying glass handy, as mites are so small they can barely be seen with the naked eye. Like aphids, they pierce the plant tissue and suck out the sap. Symptoms range from tiny yellow spots, distorted leaves and withered, discolored flowers to a webbing on buds, leaf undersides and between stems.
You can try to remove them by spraying the chrysanthemums forcefully with water at least three times, but two-spotted spider mites may prove difficult to eliminate. Your best chance is to catch the infestation in the early stage (indicated by the yellow spots) and use insecticidal soap. Other than that, you may have to destroy plants or portions severely infested with these mites. - The tiny larvae of gall midges are yellow to orange, and they live and feed within bulges in the plant. These bulges, which can be spotted due to coloration, are called galls and are swellings in the plant tissue caused by the larvae as they bore through it. Adult gall midges look like fungus gnats and are tiny with long, thin antennae.
Since these pests are hard to kill using insecticide, you'll need to prune away and destroy any galls when you spot them. If the infestation is severe, remove entire chrysanthemums to protect other surrounding plants.
