Allelopathy refers to the direct or indirect effect that a plant has on the plant or surrounding plants (including microorganisms) by releasing chemicals to the environment. According to the above definitions, the following are not allergic:. ['After the pesticide sprayed on ginseng is absorbed by the soil, it will kill the nitrifying bacteria and ammoniating bacteria in the soil.', 'The leaves and peels of walnut trees will release glucose to walnut quinones, which will kill the plants under the walnut tree.', 'The phenolic substances secreted from eucalyptus leaves can inhibit the growth of nearby flax after being washed down by rainwater.', 'Hydroxamic acid is produced after rye residues are decomposed by microorganisms, affecting their own growth and development.']