Chrysanthemum Pests and Biological Controls

This winter I faced two problems in my chrysanthemum plants. One is caterpillar and the other is aphid. Both of them are problematic, but aphid is the most problem. Sometimes chemicals are effective, but as you know, it is also make another problem to the plants. So, I think I need biological control. I am new in this field, so that I am really interested to learn all of knowledge related to floriculture. This time I want to write about chrysanthemum's enemies (Aphids and Caterpillar) and how to kill them without making any other problems to the plants.

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Aphids

Aphids are one of the most common plant pest insects. Although common, they usually do not occur in damaging numbers. Aphids have thin legs and long, thin antennae. They also have long slender "beaks" or mouthparts, which they stick into plants to suck the juices from the plant tissue. When aphids population build up quickly, damage to the plant can occur. The result is wilting and yellowing, which can cause leaves to curl, leading eventually to the plant's death.

I applied Imidacloprid to my chrysanthemum plants. The aphids were died. But let see what happen to the ground. From wikipedia, I found that this chemical is a potential water-ground contaminant. This chemical is also dangerous to the human because it may changes the human lymphocytes.

The biological controls for aphids are lady beetles, lacewings, and flower flies. There is also prasitized aphids, called mummies. When the minute wasp emerges from the aphid mummy, a small hole is left in the aphid's back. It takes only a few predators and parasites on a small plant or branch terminal to reduce aphid populations.

Actually we can also remove the aphids physically by hand. Another way is using strong water sprays from a garden hose. But this needs a lot of time and energy.



Caterpillar

Caterpillar is also an enemy for my chrysanthemum plants. They grow fast and destroy the chrysanthemum leaves. Caterpillar shows the basic body of a larval insect. Certain groups of larvae especially caterpillars and sawfly larvae, have auxiliary legs, called prolegs on the abdomen.

Caterpillar can be removed by chemicals. If you have a lot of time, you can pick it one by one. Otherwise we can choose the most savely killer or by applying biological control. Bacillus thuringiensis can be very effective against caterpillars, but other natural enemies are of limited value. Green lacewings are also known as caterpillar predator. They feed caterpillar's eggs.

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References:
1. http://ag.udel.edu/extension/horticulture/pdf/ent/ent-20.pdf
2. Susan E. Rice Mahr, et al. _____. Biological control of insects and other pests of greenhouse crops. North Central Regional Publocation 581. USA.
3. http://en.wikipedia.org/wiki/Imidacloprid

Pictures taken from:
1. http://www.osvescen.org/cheap/B003OZ1OL2/1000-Green-Lacewing-Eggs-Larvae-eat-10M-Aphids-per-Day
2. http://www.yourgardeninginfo.com/beware-of-garden-pests-for-flower-crops
3. http://www.lternet.edu/gallery/sites/kbs/KBS_Ha_eating_SBA.jpg.html
4. http://www.chrysanthemums.info/ailments/p-aphids.htm