Nematodes - Evil Flowers

There are thousands of types of nematodes. All living beings, animals or plants, can be attacked or parasitized by them. However, there is a general rule in biology about nematodes that seems to have no exception: nematodes that attack animals do not attack plants and vice versa. Within each of these groups, naturally, there is specificity. Thus, the nematode that parasitizes the whale does not parasitize the dog. However, there are several nematodes that parasitize different species of animals, including humans. This principle also applies to plant nematodes. Therefore, there are several nematodes that parasitize various ornamental plants and that are also pests of many of our most economically important crops.

The table lists several species of ornamental plants and representatives of different genera of associated nematodes, many of which are considered key pests of many of our crops. This table was constructed based on data obtained from the analysis of samples of ornamental plants, starting in 1992, at the Nematology Laboratory of the Department of Plant Health at UNESP/FCAV, Jaboticabal Campus (SP). These data represent a warning for all citizens.

What should we do, then, with the pot of an ornamental plant that we buy at a fair or in a market, after the plant completes its cycle and dies? What if the plant dies before the expected time? Could the plant's death have been caused by a nematode? What could happen if the pot containing millions of nematodes were thrown into an area close to a host crop? Distinguished readers are being alerted to the risks of unconsciously acting as dispersing agents for very harmful pests.

As nematodes are microscopic and, in most cases, do not produce specific symptoms in attacked plants, they go unnoticed. Therefore, if your ornamental plant dies from an unknown cause, apply boiling water to the pot before placing it in the trash. The lethal temperature for the vast majority of nematodes is only 52oC. With this small gesture you can avoid a catastrophe. Nematodes cause devastating losses, reducing the supply of quality produce and increasing food prices. When you travel to distant regions, inside or outside our country, do not bring plant material or soil. Bulbs and seeds can also carry nematodes inside, easily allowing them to disperse over short or long distances.

The nematode

, for example, the causal agent of a rice disease known as "white tip", can survive up to 19 years inside the seeds. Seed garlic bulbs can keep nematodes alive from one year to the next, as can bulbs of various ornamentals. Nematodes considered devastating pests of potatoes, tomatoes, beans, wheat and countless other important crops are found in neighboring countries, including our Mercosur partners, but have not yet reached Brazil.

Unlike other pests that fly or are carried by winds, nematodes do not spread through their own resources. Therefore, these pests will only reach our country if they are brought. Seeds, seedlings and soil adhering to machines and various vehicles are the main means of dispersion. It is, therefore, the duty of each Brazilian to prevent the spread of these pests, acting consciously to avoid their introduction into our territory. The figure illustrates stages of development of

, one of the most devastating coffee nematodes (

). This pest attacks a large number of crops, including several ornamentals. Therefore, producers and consumers should also seek to know these pests. With the contribution of every citizen, we will keep many of our cultivation areas free from many of them.

Katia van Leeuwen and Jaime Maia dos Santos

UNESP

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