Eelworms

Microscopic nematode worms, invisible to the naked eye. Some attack plants, while others are beneficial, attacking slugs and larvae of weevils and other pests. See Potato cyst eelworm. 

Symptoms Young plants wilt and die leaves and stems of older plants become soft and rotten. Larvae bore into onion bulbs, which then rot Most severe in early to midsummer. May be confused with stem eelworm and onion white rot... 

Damage is usually caused by a blockage of the water-conducting tissues of the stem, starving the leaves of water. Wilts can persist in the soil for several years, entering plants through wounds. Commonly associated with eelworm attack. Some wilts, e.g., of China asters and peas, are host-specific, while others attack a wide range of plants. 

Pesticides are chemicals or biological substances used to kill or control pests. They fall into three major classes insecticides, fungicides, and herbicides (or weed killers). There are also rodenticides (for control of vertebrate pests), nematicides (to kill eelworms, etc.), molluscicides (to kill slugs and snails), and acaricides (to kill mites). These chemicals are typically manmade synthetic organic compounds, but there are exceptions which occur naturally that are plant derivatives or naturally occurring inorganic minerals. 

Plant-parasitic nematodes, also called eelworms, are small transparent cylindrical organisms usually between 0.5 and 3.0 mm in length. By means of a stylet in the form of a... 

Cephalosporiopsis carnivora Drechsler (1969) was observed on free-living Rhabditis sp., but is not available in culture for further study. It is characterized by discrete, short flask-shaped phialides in moderately verticillate, generally erect conidiophores and elongate-ellipsoid or somewhat obovoid conidia, mostly divided by a cross-wall at a slight median constriction, mostly 3.0-4.2 X 1.7-2.2 pm. Frequently 1 or 2 conidia were seen adhering to the forward profile of an actively motile eelworm. This statement suggests an adhesive mechanism that would place the species near Haptocillium. 

Nematodes or eelworms are microsoopio roundworms which live in soil, decomposing organic matter, fresh or salt water, or on living host plants, fungi, insects and animals. Nematodes can survive up to six weeks without food and are unaffected by freezing. With eight billion nematodes in each acre of soil, they are one of the most numerous creatures on earth. 

Figure 238 Mycophagous eelworm (top) and Saprophagous eelworm. Note stylet in mouth tube of former.

Although saprophagous eelworms are not primary pathogens, their presence indicates improper hygiene or imbalanced growing conditions. For this reason, control measures focu on prevention rather than treatment. In fact, there are no practical means to treat infested areas that would not likewise harm the mushroom mycelium. 

Nematodes, or eelworms, are abundant in nature, being widely distributed as parasites of vertebrate and invertebrate animals, and of plants. Free-living nematodes also constitute an important part of the soil fauna, being more numerous than any other animal of comparable size (Christie, 1959). Nielsen (1967) states that there are about 10,000 known species of Nematoda but of these only about 2,000 are soil inhabitants. These soil species are for the most part of microscopic or near-microscopic size, whereas the animal parasitic species are mostly visible to the naked eye. The average length of the kinds that occur in soil is about one millimeter. 

Beet eelworm cyst hatching factor beet, rape... 

Cabbage eelworm cyst hatching factor black mustard... 

Use Anthelmintic, active against eelworms and hookworms. Excessive doses lead to severe, often lethal poisonings so that A. has been replaced by synthetic anthelmintics with specific activities. 

Oil of Chenopodium (wormseed oil). Essential oil obtained from Chenopodium ambrosioides var. anthel-minticum (goosefoot), previously used in humans and animals against worm parasites (eelworms and hookworms). O. C. is no longer used in human medicine on account of its side effects. O.C. contains mainly ascaridole (60-75%), ascaridole glycol, p-cymol (20-30%, see cymenes), a-terpinene, limo-nene. 

Nettlehead, first described in 1894, is economically the most serious of the virus diseases. At least two viruses are involved Arabis mosaic virus and Prunus necrotic ringspot virus. Both are sap-transmissible and the former is carried by the eelworm Xiphinema in the soil. The same two viruses are also responsible for another virus disease, split-leaf blotch. 

Other pests which may infect hops include the clay-coloured weevil (Otiorrhynchus singularis L.), the hop root weevil (Epipolaeus caliginosus F.), wireworms (Agriotes spp.), leather-jackets (Tipula spp.), slugs, and eelworms. 

Unsegmented eelworms belong to a group of animals termed nematodes, which attack the roots of crop plants causing considerable damage. In order to achieve efficient control of nematodes, two types of nematicides have been used. 

There has recently been a large increase in interest in the use of red clover and a much needed and very welcome reinstatement of the breeding programme for this legnme at IGER (now IBERS - the Institute of Biological, Environmental and Rural Sciences) Aberystwyth. Important objectives for the plant breeders will be increased longevity, coupled with improved resistaiKe to clover rot and stem eelworm. 

Stem eelworm (Ditylenchus dipsaci) is an important seed-bome pest of field beans. Home-saved seed should always be tested for it and the status of certified seed should be ascertained as well. 

Agonomycetes. Also known as Mycelia Sterilia. Lacking spores, they are not strictly speaking mitosporic, but are included with mitosporic fungi for convenience. Some have morphological features such as sclerotia or traps for eelworms that facilitate identification. 

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