ENVIRONMENTAL CONSEQUENCES in rocky mountain coniferous ...

RESIDUE AND FIRE MANAGEMENT TO "CONTROL" INSECTS AND DISEASE
A multitude of interactions with several different diseases and a variety of
insect species and groups (with different habits and economic impact) exist with
both residue and fire management. In discussion some of these interactions, I use
the word "control" with caution and interpret the word "residue" very broadly.
Diseases
The most noteworthy examples of fire and residue mangement involve three forest
diseases: brownspot need1 e bl ight, Scirrhia acicola e earn. ) Siggers, dwarf mistle-
toe, and root pathogens, principally Fomes an-Fr.) Cke.
As noted by Martin and others (1977) and Miller (1978), prescribed burning to
control brownspot needle blight on long leaf pine, Pinus palustris L., seedlings
provides a classic and outstanding example of the use of fire to control disease.
Fire has been implicated in many aspects of the spread and intensification of dwarf
mistletoes (Alexander and Hawksworth l975), and fire is often used to burn the slash
of infected trees in order to reduce the infection of new seed1 ings (Martin and
others 19771. In discussing fire and dwarf mistletoe relationships in the northern
Rocky Mountains, Wicker and Leaphart (1 976) plead for planning management act-ivi ties
on the basis of habitat types. The authors are convinced that a1 though fire, pests,
and plants should be managed, "Man should strtve to mana e the total forest ecosystem
and not to control or eradicate certain segments of it" 9 Wicker and Leaphart 1976).
Repeated burning is known to have a suppressive effect on certain root pathogens
(Froelich and others 1478). Prescribed fire reduces the incidence of Fomes annosus
root rot (Martin and others 1977) and controls many other plant diseasmardisan
1976; Haryey and others 1976).
There are some other fire-disease interactions. Fire can act as a sterilizing
agent in controlling some plant diseases by destroying insects acting as plant
disease vectors (Ahlgren and Ah1 ren 1960). Fire scars can serve as avenues of
entry for many forest pathogens 9 Harvey and others 1976j., and infested residues act
as reservoirs that tend to propogate and increase pathological activity (Nelspn and
Harvey 1974; Mitchell and Sartwell 1974; Parmeter 1977). In some cases fire may
favor the Increase of disease by producing thick stands of the host plant, thereby
inducing mu1 tip1 ication and spread (Ahlgren and Ahlgren 1960).
Insects
In the late 1800's and early 1900's, entomologists used prescribed fire to
suppress insect populations (Komarek 197O), but fire prevention campaigns and insecti -
cidal developments infl uenced 1 ater generations of entomol ogists to use methods
other than fire. "Today, modern fire-use technology and renewed interest in al'terna-
tive methods make fire attractive again as an insect management tool" (Miller 1978).
Komarek (1970) summarfzes the actions of fire on regulating insect populations and
lists several variables that must be considered when studying or evaluating the
effect of fire. Yet, he concludes that ". . .to what extent and how these changes
occur has not been investigated," and "There appears to have been very little