Integrated Pest Management (IPM) in Forestry - ACS Publications

7 Integrated Pest Management (IPM) in Forestry JOHN NEISESS

Downloaded by UNIV LAVAL on July 11, 2016 | http://pubs.acs.org Publication Date: January 16, 1984 | doi: 10.1021/bk-1984-0238.ch007

U.S. Department of Agriculture, Forest Pest Management, P.O. Box 2417, Washington, DC 20013

Until about 10 years ago, pest management in forestry was practiced much like fire management. When insects, diseases, pocket gophers, competing vegetation, or other pests increased to outbreak levels, forest managers geared up and put the so-called fire out. However, over the past few years, forest managers have been changing their pest management philosophy from a reliance on direct suppression of pests when they reach damaging levels to an integrated (or IPM) approach to preventing or reducing the resource damage caused by pests. In 1980, an evaluation of Forest Service pest management programs by the Center for Natural Areas concluded that even though forest managers did not fully understand IPM terminology and policies, they were doing an adequate job of implementing the concepts of IPM, but calling it something else. What Is IPM? The Forest Service Manual defines IPM as "a systematic decision -making process and the resultant management actions which derive from considerations of pest-host systems and evaluation of alternatives for managing pest populations at levels consistent with resource management objectives." In other words, IPM consists of two basic elements: the decisionmaking process and the action program. The decision process begins with the detection of the pest and evaluation of its impact on the resource. Detection and evaluation usually involve site visits by resource or pest management specialists to determine the density of the pest and the condition of the site. Aerial photography and pheromone trapping have improved detection of insect pests. Pheromone traps are currently being used to help monitor the building Douglas-fir tussock moth (Ovgyia pseudotsugata (McDunnough)) populations in the Northwest. Early detection permits different action programs than are used when a pest population reaches outbreak proportions. In 1977, This chapter not subject to U.S. copyright. Published 1984, American Chemical Society

Garner and Harvey; Chemical and Biological Controls in Forestry ACS Symposium Series; American Chemical Society: Washington, DC, 1984.


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f o r example, the F o r e s t S e r v i c e i n i t i a t e d a p r o j e c t to determine i f e a r l y treatment of western spruce budworm (Chovistoneuva oecidentdlis Freeman) would reduce the budworm to such a l e v e l that subsequent treatment would not be needed. Measurements of egg mass d e n s i t i e s f o r 6 years i n t r e a t e d versus untreated areas have shown the success of t h i s e a r l y treatment s t r a t e g y ( F i g u r e 1). The decisionmaking process a l s o i d e n t i f i e s the resource management o b j e c t i v e and evaluates the cost of pest c o n t r o l schemes and t h e i r impacts on the v a r i o u s resources a s s o c i a t e d w i t h the s i t e . The pest c o n t r o l scheme must be compatible w i t h the o v e r a l l management and economics of the resources being managed. An i n s e c t outbreak, t h e r e f o r e , would not be c o n t r o l l e d on a s i t e being managed f o r w i l d l i f e i f the r e d u c t i o n i n the timber resource improved the s i t e f o r w i l d l i f e without g r e a t l y damaging other resource v a l u e s . The a c t i o n program c o n s i s t s of a mixture of p r e v e n t i o n and d i r e c t suppression a c t i v i t i e s . P r e v e n t i o n i n c l u d e s those a c t i v i t i e s that make the f o r e s t l e s s conducive to pest outbreaks. D i r e c t suppression may i n v o l v e one or more c o n t r o l t a c t i c s d i r e c t e d a t the pest i t s e l f . B i o l o g i c a l or chemical p e s t i c i d e s , mechanical methods, use of p a r a s i t e s , and f i r e are a few of the a v a i l a b l e t a c t i c s . For example, a l t e r n a t i v e s used t o c o n t r o l mountain pine b e e t l e (Dendvoetonue pondevosae Hopkins) i n an IPM program i n c l u d e the f o l l o w i n g p r e v e n t i o n and d i r e c t suppression a l t e r n a t i v e s : (1) Do n o t h i n g , (2) S i l v i c u l t u r a l c o n t r o l to m a i n t a i n a vigorous stand, (3X D i r e c t c o n t r o l accomplished by f e l l i n g and removing i n f e s t e d t r e e s or by f e l l i n g and burning or c h e m i c a l l y t r e a t i n g i n f e s t e d t r e e s , or (4) P r o t e c t i v e s p r a y i n g of high-value t r e e s w i t h i n s e c t i c i d e s . Note that chemical p e s t i c i d e s are very much a p a r t of IPM. In a f u l l y implemented IPM program, however, chemical use p a t t e r n s may change because of e a r l y d e t e c t i o n , which could reduce the amounts of p e s t i c i d e s used. Examples of IPM i n F o r e s t r y An IPM program undertaken around D i l l o n , Colorado, i n 1982, e x e m p l i f i e s the combination of treatments used to manage a mountain pine b e e t l e outbreak i n lodgepole pine. D i r e c t suppression and p r e v e n t i v e s p r a y i n g were important to the D i l l o n p r o j e c t because of the h i g h r e c r e a t i o n a l v a l u e s . But these a c t i v i t i e s were only intended to l i m i t immediate t r e e l o s s e s and a l l o w time to implement c u l t u r a l or s i l v i c u l t u r a l treatments. More than 87,000 i n f e s t e d t r e e s on S t a t e , p r i v a t e , and F e d e r a l lands i n the D i l l o n area were e i t h e r cut and removed or cut and t r e a t e d w i t h l i n d a n e or ethylene dibromide (Table I ) . The cut timber was made a v a i l a b l e t o the p u b l i c as fuelwood. S l a s h d i s p o s a l was a l s o implemented on 39,000 acres i n order to reduce the p o s s i b i l i t y of engraver b e e t l e (Ips spp.) b u i l d u p i n the s l a s h r e s u l t i n g from salvage o p e r a t i o n s . C a r b a r y l was a p p l i e d as


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Integrated Pest Management


50-|

O-f

1977

nifmiwimtiiniiWHinTfT-

1978

1979

,

YEARS

1980

,

1981

-,

1982

F i g u r e 1. Comparison of average number of western spruce budworm egg masses i n t r e a t e d and untreated areas, New Mexico.


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a p r e v e n t i v e spray on 26,000 high-value t r e e s i n campgrounds and r e c r e a t i o n a l areas. This preventive spraying w i l l be continued i n high-use areas w h i l e the outbreak p e r s i s t s .

Table I . Mixture of treatment s t r a t e g i e s used i n the 1982 D i l l o n , Colorado, IPM p r o j e c t t o c o n t r o l mountain pine b e e t l e


Treatment

MPB t r e e s felled/removed MPB t r e e s f e l l e d / i n s e c t i c i d e t r e a t e d Preventive spraying

Thinning Slash disposal

U n i t s Treated

18,455 t r e e s 68,953 t r e e s 26,000 t r e e s

54 acres 3,940 acres

The main e f f o r t on Forest S e r v i c e lands w i l l be d i r e c t e d a t the 32,000 acres of pine t h a t have been i d e n t i f i e d as s u s c e p t i b l e to b e e t l e s and on operable t e r r a i n . Plans c a l l f o r h a r v e s t i n g of the mature and overmature s u s c e p t i b l e pines over a 15- t o 30-year p e r i o d . I n order t o l i m i t the impact on the r e c r e a t i o n a l and e s t h e t i c q u a l i t i e s , s m a l l c l e a r c u t s and patch cuts w i l l be the common treatment used to break up the l a r g e continuous areas of s u s c e p t i b l e t r e e s i n t o s m a l l e r areas. Immature stands w i l l be thinned t o prevent s t a g n a t i o n and reduce f u t u r e s u s c e p t i b l i t y . An a c t i o n program such as the one around D i l l o n i s based on current knowledge about the pest and i t s host; research and knowledge are key components i n IPM. The r o l e of the pest i n the f o r e s t ecosystem must be understood when making management p r e s c r i p t i o n s , and resource managers must be able t o p r e d i c t the e f f e c t s of v a r i o u s management p r a c t i c e s on pest organisms, d e s i r e d p l a n t s , and the environment. I t i s important t o understand t h a t i f a pest i s t r e a t e d d i r e c t l y without c o n s i d e r i n g the cause of the outbreak, the pest may reappear once the treatment i s f i n i s h e d . I f the cause i s t r e a t e d , however, the r e s u l t w i l l g e n e r a l l y be long-term p r o t e c t i o n . In developing g u i d e l i n e s f o r c o n t r o l l i n g mountain pine b e e t l e , pest management s p e c i a l i s t s drew on t h e i r knowledge of s e v e r a l important b i o l o g i c a l f a c t s about the b e e t l e and i t s i n t e r a c t i o n s w i t h the host t r e e s : (1) The mountain pine b e e t l e k i l l s p r o p o r t i o n a l l y more l a r g e diameter t r e e s than s m a l l diameter t r e e s during an i n f e s t a t i o n , (2) B e e t l e r e p r o d u c t i o n i s d i r e c t l y r e l a t e d to phloem t h i c k n e s s , (3) Phloem i s u s u a l l y t h i c k e r i n l a r g e diameter t r e e s , and (4) I n f e s t a t i o n s seldom develop i n stands l e s s



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than 60 t o 80 years of age. Although they disagree about the e f f e c t s of stand d e n s i t y on p o t e n t i a l b e e t l e outbreaks, most pest management s p e c i a l i s t s b e l i e v e t h a t overstocked, stagnated stands are more s u s c e p t i b l e t o b e e t l e a t t a c k than vigorous stands. Another key component t o f u l l y implementing IPM i n f o r e s t r y i s i n t e g r a t i n g pest management i n t o f o r e s t management decisionmaking. This r e q u i r e s resource managers t o accept g r e a t e r r e s p o n s i b i l i t y f o r pest p r e v e n t i o n i n t h e i r normal a c t i v i t i e s . Guidelines f o r preventing pest outbreaks need t o be developed and then used by the resource managers as they develop and implement management plans o r set p r i o r i t i e s f o r s i t e s needing treatment. One example where pest p r e v e n t i o n i s being considered by the f o r e s t manager i s the c o n t r o l of dwarf m i s t l e t o e (Arceuthobium spp.). Pest management s p e c i a l i s t s have done t h e i r p a r t by i n c l u d i n g the understanding of the b a s i c b i o l o g y and pest/host r e l a t i o n s h i p s i n t o c o n t r o l g u i d e l i n e s so t h a t s i l v i c u l t u r i s t s can determine the s e v e r i t y of an i n f e c t i o n i n a stand. When d e a l i n g w i t h dwarf m i s t l e t o e , the g u i d e l i n e s c a l l f o r s i x a c t i o n a l t e r n a t i v e s : (1) No a c t i o n , (2) Conversion t o nonhost s p e c i e s , (3) C l e a r c u t , (4) Seed t r e e cuts w i t h subsequent removal of seed t r e e s , (5) Complete s a n i t a t i o n , o r (6) P a r t i a l s a n i t a t i o n which reduces but does not e l i m i n a t e t h e pest. Each of these a l t e r n a t i v e s i s evaluated by the manager i n l i g h t of the i n f o r m a t i o n about s e v e r i t y of the i n f e s t a t i o n and b a s i c stand i n f o r m a t i o n (age, s t o c k i n g d e n s i t y , composition, and growth p o t e n t i a l ) , the management o b j e c t i v e , and the economics of t h e s i t u a t i o n . Pest management s p e c i a l i s t s have made the decisionmaking e a s i e r by i n c o r p o r a t i n g the growth impacts of dwarf m i s t l e t o e i n t o a number of models used t o p r e d i c t timber y i e l d s . Given s p e c i f i c stand c o n d i t i o n s , these models a l l o w the manager t o p r e d i c t t r e e growth f o l l o w i n g v a r i o u s treatment a l t e r n a t i v e s . G e n e r a l l y , one o r more of these treatment a l t e r n a t i v e s can be accomplished w i t h i n normal s i l v i c u l t u r a l p r a c t i c e s . S a n i t a t i o n c u t t i n g s , f o r example, can be combined w i t h planned t h i n n i n g o r timber stand improvement o p e r a t i o n s . Although r e s e a r c h has provided a great deal of knowledge about p e s t s , and pest management i s being i n t e g r a t e d i n t o resource management, many unanswered questions remain. More research i s needed i n pest/host r e l a t i o n s h i p s and the impact and i n t e r a c t i o n s of v a r i o u s treatment a l t e r n a t i v e s . The knowledge base f o r implementing an i n t e g r a t e d v e g e t a t i o n management program i s a case i n p o i n t . Research has provided a great d e a l of i n f o r m a t i o n about the b a s i c b i o l o g y of the i n d i v i d u a l crop t r e e s and brush s p e c i e s . However, l i t t l e i s known about the c o m p e t i t i v e a b i l i t y of v a r i o u s types of v e g e t a t i v e cover. And other than i n f o r m a t i o n on the e f f e c t s of h e r b i c i d e s , l i t t l e i n f o r m a t i o n e x i s t s on the environmental impacts of d i r e c t or c u l t u r a l treatments or on the comparative b e n e f i t s of these treatments. These t e c h n i c a l l i m i t a t i o n s mean t h a t d e c i s i o n s t o c o n t r o l competing v e g e t a t i o n are g e n e r a l l y based on the experience of the manager and are o f t e n



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made only a f t e r the impacts of competing v e g e t a t i o n are c l e a r l y evident and some l o s s i n growth or s e e d l i n g s u r v i v a l has occurred. Although the knowledge base f o r an i n t e g r a t e d v e g e t a t i o n management program i s l i m i t e d , much has been learned and put i n t o p r a c t i c e . The manager has a number of d i r e c t treatment a l t e r n a t i v e s , which i n c l u d e u s i n g h e r b i c i d e s , mechanical removal, hand c u t t i n g or grubbing, burning, as w e l l as doing nothing. Vegetation management s p e c i a l i s t s have a l s o learned to i d e n t i f y p o t e n t i a l weed problems and to p r e s c r i b e c u l t u r a l or i n d i r e c t treatments that may reduce the need f o r d i r e c t treatment. C u l t u r a l p r a c t i c e s important to an i n t e g r a t e d v e g e t a t i o n management program i n c l u d e use of l a r g e r , more vigorous growing stock to hasten r e f o r e s t a t i o n , use of shade-tolerant species on s i t e s where competing v e g e t a t i o n i s a problem, and shortening the time between h a r v e s t i n g and p l a n t i n g so that the s i t e does not become occupied w i t h brush. The treatments used on the Willamette N a t i o n a l Forest i n Oregon during 1982 to c o n t r o l competing v e g e t a t i o n exemplify the Forest S e r v i c e e f f o r t to i n t e g r a t e the v a r i o u s a l t e r n a t i v e s i n s i t e p r e p a r a t i o n and r e l e a s e programs (Table I I ) .

Table I I . S e l e c t e d v e g e t a t i o n management a l t e r n a t i v e s used on the W i l l a m e t t e N a t i o n a l F o r e s t , Oregon, 1982

Treatment

Heavy machinery Hand c u t t i n g Hand c u t t i n g / b u r n i n g Hand c u t t i n g / h e r b i c i d e Hand p u l l i n g and grubbing Herbicides Aerial Hand No treatment

Acres

123 320 162 1,448 463 2,337 761 1,247

Another problem w i t h implementing IPM i n f o r e s t r y i s a r e l u c t a n c e of resource managers to heed the warnings and recommendations of pest management s p e c i a l i s t s . The c u r r e n t outbreaks of mountain pine b e e t l e t y p i f y t h i s r e l u c t a n c e . Most of the stands c u r r e n t l y under a t t a c k are i n areas of the country that have been managed p r i m a r i l y f o r r e c r e a t i o n or w i l d l i f e v a l u e s , not timber p r o d u c t i o n . Therefore, managers have n a t u r a l l y been r e l u c t a n t to l o c a t e c l e a r c u t s i n areas around s k i r e s o r t s or f a v o r i t e camping areas, even though the entomologists p r e d i c t e d



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t h a t the unmanaged stands were becoming " b e e t l e b a i t . " Programs l i k e the D i l l o n mountain pine b e e t l e p r o j e c t are s l o w l y t u r n i n g t h i s r e l u c t a n c e around. In c o n c l u s i o n , the management of dwarf m i s t l e t o e , mountain pine b e e t l e , and competing v e g e t a t i o n shows t h a t IPM has achieved some success a t becoming a proven o p t i o n i n pest management. IPM o f f e r s indepth e v a l u a t i o n s of c o n d i t i o n s t h a t cause pest problems and a c t i o n programs t h a t are long l a s t i n g and environmentally a c c e p t a b l e . Large advances have been made i n i n t e g r a t i n g pest management i n t o normal resource management p r a c t i c e s , but progress w i l l continue t o be slow. The i n t e n s i v e management r e q u i r e d t o prevent pest outbreaks i s being p r a c t i c e d on only l i m i t e d acreage. As long as our country continues t o have vast acres of unmanaged stands, f o r e s t resource managers w i l l s t i l l have t o r e l y on d i r e c t treatments t o c o n t r o l the damage caused by pest outbreaks. I n these cases, our IPM e f f o r t s w i l l be l i m i t e d t o e a r l i e r d e t e c t i o n methods and i n t e g r a t e d d i r e c t suppression when needed.

RECEIVED September

9,

1983


Integrated Pest Management (IPM) in Forestry - ACS Publications

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