Infestation fungal

Obviously, one looks for causes. That declines in one or another species have natural factor etiologies is unequivocal. The demise of American elms and of the chestnut were due to natural factors. Insect infestations, bacterial and fungal diseases, hurricanes, floods, freezes, droughts and many other stresses can cause extensive tree death (5). But in such declines typically only a single species is affected or climatic events caused decline in a delimited area. In almost all declines caused by natural events, the causal factors can be identified we know their precise etiologies. Natural events are always part of the natural environment and must be factored in when evaluating forest declines (Table I). 

Viruses/bacteria Fungal disease Insect infestation Mineral recycling Indigenous metals... 

Mycotoxins can also cause esophageal and liver cancers in humans and are associated with stunting in children. These problems are especially acute in rural Africa where farmers store a years supply of corn in wicker cribs that are open to the sun, weather, infestation by beetle and weevil larvae, and fungal contamination (Wu 2006). 

Enhanced resistance to disease in plants after an initial infection has fascinated observers for over 100 years. A review of the subject by Chester in 1933 contains 201 references (Jj. "Immunization", "acquired systemic resistance", or "induced resistance" of plants have been reviewed in recent years (2-11). We shall not exhaustively review the literature, but shall focus on general principles and phenomena of particular relevance to the use of "plant immunization" for the practical control of disease. This paper will stress examples from our own research program, but wi1i also include literature citations to provide the reader with an appreciation of important research contributions of others previously and presently active in the field. Most examples presented will deal with fungal, bacterial, or viral diseases of crop plants, but similar principles may apply to infestations by nematodes and, possibly, insects. 

Fungal diseases of weeds are common, but until recently they have not received much research attention plant pathologists have emphasized research to control diseases of economic crops. Weed diseases have often been noted by weed scientists as confounding factors in weed research plots and by growers faced with severe weed infestations in crops for which chemical herbicides are either unavailable or inadequate to control a particular weed. 

Apart from the insecticides and herbicides already discussed, there are many other kinds of pesticides in use. These range from rodenticides (chemicals designed to kiU mainly rats and mice) to fungicides, nemato-cides, and molluscicides (which target fungal infections of crops and animals, infestations of animals by nematode worms, and organisms such as slugs, respectively). Some of these have been associated with cases of... 

Kaltenpoth M, Gottler W, Herzner G, Strohm E. Symbiotic bacteria protect wasp larvae from fungal infestation. Curr. Biol. 2005 15 475-479. 

Insect pests such as yucca plant bugs anc scales are more prevalent and likely to cause damage where yuccas are native. Aphids ma> infest Adam s-needle see Leaves, stems, and buds distorted, sticky clusters of small insects on page 177 for controls. Fungal leaf spot may appear and are best controlled with cu tural practices Limit excess water on foliagr and remove severely infected plant parts. 

Protection Offered Control aphids, garden webworms, leafminers, and tent caterpillars by pruning infested plant parts. Pruning also limits the spread of foliar diseases and conditions that promote fungal growth. 

Tests for fungal and/or microbiological contamination, fumigant residues (if applicable), mycotoxins, pest-infestations, radioactivity and their acceptable limits. 

Any treatment, such as fumigation, used to reduce fungal or microbiological contamination or other infestation, together with methods of determining the extent of such contamination and potential residues, should be documented. Instructions on the conduct of such procedures should be available and should include details of the process, tests and allowable limits for residues together with specifications for apparatus used. 

The personnel of quality control units should have the necessary expertise in herbal medicines to enable them to carry out identification tests and recognize adulteration, the presence of fungal growth or infestations and lack of uniformity in a consignment of herbal materials. 

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