Chrysanthemum foliar nematode

Aphelenchoides ritzemabosi, commonly known as the chrysanthemum foliar nematode, is a microscopic worm within the phylum Nematoda. As a serious plant pathogen, it causes significant damage to foliage, flowers, and stems, leading to severe economic losses in floriculture and ornamental nursery production.

The nematode targets a wide variety of plants, with Chrysanthemum species being the primary hosts. Affected plants often exhibit interveinal chlorosis, which progresses into dark brown or black necrotic lesions. These spots are typically delimited by veins, giving the leaf a characteristic mosaic or marbled appearance before the tissue eventually dies and drops off.

The biology of Aphelenchoides ritzemabosi is dependent on high moisture levels. The nematodes migrate upward along the stems during periods of rain or heavy dew, entering the plant through stomata. Once inside, they move through the intercellular spaces, feeding on parenchyma cells and completing their life cycle within the host tissue.

Development is most rapid under warm, humid conditions. This pathogen is highly resilient and can survive for months in crop debris, soil, or even within dormant buds. Its ability to persist in the environment makes it a difficult challenge for growers who do not adhere to strict sanitation protocols throughout the growing season.

Integrated pest management strategies are essential to mitigate the spread of this nematode:

• Strict quarantine and inspection of all incoming plant material to avoid introduction.
• Hot water treatment of cuttings (soaking at 45–48°C for several minutes) to eliminate nematodes.
• Maintaining optimal spacing to improve airflow and reduce leaf wetness.
• Removing and destroying all symptomatic plants and infested debris.
• Avoiding overhead irrigation to prevent the spread of the pathogen between leaves and plants.