INTRODUCTION

During October 1958 a visit was made to the Northeastern Forest Insect Laboratory, New Haven, Connecticut. A week was devoted to a survey of shoot moth damage in red pine plantations near New Haven. In this area are the oldest known infested red pine plan-tations in the United States. Research on the shoot moth was con-ducted in these stands during the 1930's by Dr. R. B. Friend et al. However, since that time no information has been published on the insect in these stands. To broaden our outlook, develop research techniques, and better estimate the development of shoot moth in-fested red pine in the Lake States, the old infested plantations in the Northeast were re-examined in 1958--20 years after the studies of Dr. Friend.

Many plantations on the Eli Whitney Forest near Mew Haven, and others in the vicinity of New Britain, Connecticut, were examined. From these, four representative plantations were selec-ted for study: (1) a plantation previously damaged but recovered, (2) a stand damaged continuously, (3) one infested but not damaged, and (4) an infested stand containing both fast and slow growing trees. In these four plantations, data were obtained concerning stand development and shoot moth impact.

Fig. 1. -- A red pine plantation (I) on the Eli Whitney Forest, New Haven, Conn. These trees have been infested with the European pine shoot moth since 1926. Insect attack has resulted in forking and crook, yet 40 percent of the trees are not damaged. Compare with Friend and West (1933:Plates VI and VII

DISCUSSION

This trip has provided information on the development of the oldest shoot moth infested plantations in the United States. The technique of dating shoot moth damage up to thirty years ago has been perfected. Also, exploratory impact studies have been com-pleted. The future of Lake States infestations is perhaps more predictable.

The following discussion will cover back-dating technique, damage and cull, recovery, and Lake States applications. Detailed stand descriptions are in the Appendix.

Back-Dating Technique

It is now possible to back-date shoot moth damage for 30 years. This date was verified by revisiting one of the planta-tions studied by Friend and West (1933) with Dr. Friend (Figure 1). Characteristic shoot moth damage was obvious in the form of forks, offsets, posthorns, and spike tops. The back-dating technique manuscript has been completed and will be published (Heikkenen, 1960).

Damage and Cull

Red pine plantations may appear to be severely damaged by the shoot moth during the height of an infestation. Friend and West (1933:61) state in summary: "...A heavy infestation brings about cessation of height growth by killing the tips of both the terminals and the laterals on the upper whorls...." "A severe outbreak in a stand destroys it as an economic unit. There is no indication that an infestation will normally decline in a young red pine stand before severe injury has occurred ..."

However, by 1937 damaged plantations in this area recovered from the severe shoot moth outbreak and have not been destroyed as economic units.

That plantations are not destroyed is the result of population fluctuations and the nature of insect injury. The point of shoot moth attack is specific in both time and place; in the majority of cases an all or none affair. Once the stem reaches a given height, it is impossible for shoot moth injury to occur below that height. When the terminal reaches what will be the future merchantable height, the impact of the insect can be calculated up to that height. This may be done for any given height: when the trees reach 17 feet; cull deductions for the butt log can be determined, etc. And when insect outbreaks decline, normal height growth continues.

Fig.2. -- Theoretical yield of a stand in which there are 2 intermediate cuttings (A and B) and 1 harvest cut (C). Cull caused by the shoot moth (x and y) applied only to A and B

The amount of cull in intermediate cuttings will vary with local, current markets. In the vicinity of the NE plantations, thin-nings can be sold in 4-foot bolts, to a 3-inch top, by the ton. Culled sticks in this report are those with crook of more than 2 inches. Average cull volume is based on the number of nonmerchant-able 4-foot sticks in only the damaged trees (Figure 2). The undamaged trees are not considered as they are the final crop (C) and will not contribute to volumes composed of intermediate cut-tings (A and B). These data apply to a given site with reasonably well spaced, undamaged trees; this being the case in Plantations I and II.

Thus the impact of the shoot moth over the rotation may theo-retically be expressed by the formula:

Impact percent = (((A-x) + (B-y) … + C) / (A + B … + C) ) x 100

where:

A = first intermediate cut volume
N = shoot moth cull in terms of A volume
B = second intermediate cut volume
y = shoot moth cull in terms of B volume
C = harvest cut volume.

Shoot moth impact for a specific intermediate cut can be determined by the formula:

Impact percent = x / A 100

where:

A = volume of intermediate cut
x= shoot moth cull in terms of A volume

This formula does not consider the tree's ability to outgrow some types of damage (crook <n; 4 inches) thus reducing cull and the tree's inability to outgrow other types of damage (crook >n; 4 ) where growth only increases cull volumes. Nor is size of stick included; these factors need additional study.

When this formula is applied to Plantations I and II, the volume losses are readily calculated. In the second thinning in Plantation I, the volume loss will amount to 2.9 percent. In Plantation II the first thinning could remove all shoot moth damage to a height of 22 feet with a volume loss of 6.3 percent (Table 1).

Table 1 - The impact of the European pine shoot moth in two red pine plantations based on volume in specific intermediate cuttings
Plantation Number	No. Undamaged trees/ plot	No. Damaged trees/ plot	A,B Total No. 4-ft Sticks	x,y No. Culled Sticks	Impact Percent Pct. 4-ft Sticks Culled B/y x 100
1a	21	31	248a	7	2.8
Ib	8	13	104 a	3	2.9
II	11	35	175b	11	6.3

These data strongly suggest the ability of red pine to recover from severe shoot moth attack and the need to continue the develop-ment of accurate methods to assess shoot moth impact.

Recovery

Past serious shoot moth outbreaks in the Northeast have sub-sided and plantations recovered. The course of the outbreaks is well recorded in terms of stand damage and growth (Figures 4,6,7, and 10) Although only the severe outbreak in the early 1930's was studied, there have been minor outbreaks in 1935-36, 1943-45, 1949-50, and 1955-57.

Fig. 3. -- A normal red pine plantation located between severely damaged plantations on the Eli Whitney Forest, Yale University, New Haven, Conn., which has been infested by the shoot moth for many years.

There have been fluctuations in shoot moth damage, but the reasons for these fluctuations are not known. Site quality appears to be involved. Only plantations on poor sites appear to be con-tinually damaged (Plantation II, site index VII). Plantations on better sites are not continually damaged (Plantations I and III, site indexes II and IV, respectively). In the vicinity of New Haven, Connecticut, damaged plantations composed only a small per-centage of the total number of plantations. Numerous infested but unaffected stands were in the vicinity of severely damaged planta-tions (Figure 3).

The years in which increases in shoot moth damage occur should be investigated. Associations may be found with weather fluctua-tions; for example, the early 1930's are associated with hot, dry growing seasons as are the mid-1940's and early 1950's. Summer weather may influence the shoot moth as much, if not more, than win-ter temperatures. This could imply a "release effect" by weather conditions.

Lake States Applications

That Northeastern conditions are similar to those in the Lake States is based on the assumption that the shoot moth and red pine are genetically stable and the environment is similar in both areas.

The cull volumes in the study plantations suggest that impact in the Lake States will be concentrated in intermediate cuttings. In the most heavily damaged stands (for medium to good sites), volume losses in the first pulp thinning will amount to less than 10 percent. However, the majority of damage is correctable by pruning. The saw log crop will not be affected. Impact will vary with current local markets, stand age, and site quality.

In the Northeast, serious outbreaks have occurred in very few plantations, suggesting that it is unlikely that there will be a catastrophic, region-wide outbreak of the shoot moth in the Lake States.

The past history of fluctuations in Northeast shoot moth populations imply that the current outbreak in Lower Michigan will sub-side, but other outbreaks will occur in the future as they have in the past. These outbreaks appear to be associated with successive hot, dry growing seasons, as well as droughty sites.

SUMMARY

The oldest shoot moth infested red pine plantations in the United States have been re-examined to determine their fate and what the implications are for the Lake States.

The Northeast plantations have recovered but are still in-fested. Damage appears to fluctuate over the years and in differ-ent areas, suggesting the influence of weather and site quality. If the insect and host react similarly in the Lake States as they have in the past in the Northeast, then the current outbreak will subside in a few years. The impact of the insect will not des-troy plantations, but is usually concentrated in intermediate cut-tings.

Research is needed to determine the causal factors in shoot Roth damage fluctuations as well as techniques to assess the damage.

LITERATURE CITED

Friend, R. B. and A. S. West,Jr. 1933. The European pine shoot moth (Rhyacionia buoliana (Schiff.)). Yale Univ. Sch. For. Bul. 37. 65 pp.

Heikkenen, H. J. 1960. The identification and dating of past attacks of the European pine shoot moth on red pine. Jour. For. (in press).

APPENDIX

Plantation 1

This red pine plantation (Figure 1), located on the Eli Whitney Forest near New Haven, Connecticut, is described by Friend and West (1933:38, 45) as follows:

"0n the Saltonstall division a plantation of seventeen-year-old trees is severely damaged, and in the lower section of the plot a great majority of the leaders are dead. . . The introduction of the insect occurred in 1926, and most of the leaders were killed in 1932. In the lower (north) end of the stand very few trees show any height increment for the 1932 season. In the most severely affected part of the stand there are a few trees which will increase in height for another year or possibly two, but, practically speak-~ng, height growth fex~this group of trees has ceased, due to the death not only of the leaders but of the tips of the lateral branches of the upper whorls as well. There is no indication that adventi-tious growth can or will replace the loss. A close examination revealed that the dead leaders had started to elongate in the spring of 1932, but were killed before six inches of growth had been made. The dead terminals stand out the more conspicuously because of the loss of their needles. In many cases no laterals have~ve1oped for the past two years, so that rarely is a tree found with the full complement of lateral branches on the two uppermost whorls."

In this plantation, two dominant trees were selected and felled in October 1958. Measurements were. made of damage resulting from shoot moth attack, internodal distance, number of branches per whorl, and diameter at breast height. The mean height and mean annual number of branches per whorl have been plotted (Figure 4). The annual height growth of these two trees, determined in 1958, compares favorably with the height figures given by Friend and West (1933:45) (Table 2).

All study plantations have been numbered for cross reference.

Table 2 - A comparison of mean annual height growth taken in 1933 and 1958 for a red pine plantation (I) on the Eli Whitney Forest, Yale University
	Mean Annual Height Growth
Year	1958, Heikkenen	1933, Friend and West
1932	20.0iii	20.0iv
1931	30.0	20.7
1930	22.0	22.7
1929	24.5	22.7
1928	22.5	24.8
1927	22.0	21.3
1926	20.0	22.6
Total	161.0	154.8
Mean	23.0	22.1

Fig.4. -- Plantation I. The mean annual height growth and branches per whorl of a red pine plantation infested with the European pine shoot moth since 1926, also showing the percent of the injusr by years. (Dark trend line is height-growth in feet; zigzag line is mean annual branches per whorl; bar graph is percent injury.Dates range from 1910 to 1960. Vertical scale is height in feet.)

This stand recovered from the severe attack of 1930-1933 des-cribed by Friend and West (1933, Plates VI and VII). In 1932 apparent damage was conspicuous and most terminals were dead or bushy with few lateral branches produced from 1930 to 1931. These observations coincide with the data obtained in 1958 by back-dating. The mean annual number of branches per whorl from 1930-1933 was 2.5, 0.5,0.5, and 0.5 respectively (Figure 4). However, backdating also revealed that the plantation began to recover during the 1934 growing season and has continued to grow in a near normal manner through 1958. The shoot moth is still present, in tree 1 the terminal bud was destroyed in 1949 and 1954. In tree 2 the terminal bud was destroyed in 1949. Currently infested buds were found in the upper crowns.

Damage in this plantation was determined in two ways: a 100-percent cruise on a 1/10 acre plot (Table 3), and in another area of the plantation every 5th tree in every 5th row for a total of 21 trees (with 6 x 6 spacing, about a 1/2 acre was covered) (Table 4).

Types of shoot moth damage encountered were fork, crook, and posthorn. Height of damage was estimated by eye to the nearest foot above ground. Recognition of past damage is based on a knowl-edge of current damage and tree response (Heikkenen, 1960). Also, Dr. R. B. Friend accompanied me to this plantation and identified it as the one described on pages 38 and 45 of Friend and West (1933). Diameters (BH, OB) were taken to the nearest 1/10 inch on the 1/10 acre plot.

There are 52 trees on the 1/10 acre plot, spacing is 6 x 6 and the stand has been previously thinned. It must be emphasized that all data are based on the stand in 1958 after thinning. The basal area on this plot is 16.92 square feet, the d.b.h. of the tree with the mean BA is 7.7 inches. The mean height is 52.0 feet. The age at the end of the 1958 growing season is 34 years above BH, and estimated age is 40 years (based on a ring count at ground level). The site index is II (Spurr, 1955), 60 (Eyre and Zehngraff, 1948), and good (Rudolf, 1950).

On this plot 60 percent of the trees are damaged, conversely 40 percent are normal (Table 4). These normal trees are well dis-tributed and the conclusion is drawn that the shoot moth has not influenced the final sawlog crop of ca. 210 trees per acre

Table 3 - Types and amount of shoot moth damage to Plantation I near New Haven, Connecticut.
Height above Ground (ft)	Time in Years	Types and Amount of Damage in 4-ft Sticks
		Fork	Crook 2-in.	Crook 4-in.	Posthorn 4-in.	Total	Percent
Data based on 100 percent Cruise of a 1.10-acre Plot
1.0 - 5.5	1919-1924
5.5 - 9.5	1924-1927		1			1	2.9
9.5-13.5	1927-1929		1			1	2.9
13.5 - 17.5	1929-1931	3	1	1	1	6	17.1
17.5- 21.5	1931-1933	6	6	1		13	37.1
21.5 - 25.5	1933-1935	7	2	2		11	31.4
22.5 - 29.5	1935-1938	1		1		2	5.7
29.5 - 33.5	1938-1941			1		1	2.9
33.51 - 52.0	1941-1958
Total		17	11	6	1	35	100.0
Data taken from every 5th tree, every 5th row for ca 1/2 acre in another part of the stand
1.0- 5.5	1919-1925		1			1	6.7
5.5-9.5	1925-1927						--
9.5-13.5	1927-1929	1	2			3	20.0
13.5-17.5	1929-1931	3				3	20.0
17.5- 21.5	1931-1934	1	3	1		5	33.3
21.5-25.5	1934-1936	1				1	6.7
25.5-29.5	1936-1938						--
29.5-33.5	1938-1942						--
33.5- 37.0	1942-1945			1	1	2	13.3
37.51-52.0	1945-1958						--
Total		6	6	2	1	15	100.0

¹All damage is below height of minimum 3-inch top as of 1958.

Table 4.--Damage to individual trees and to the stand by the European pine shoot moth in Plantation I.
		Damage Percent --
Type of Damage	Number of Trees on Plot	of Damaged Trees	of the Plot
Data based on a 100 percent cruise on a 1.10 acre plot
Undamaged Trees	21__-__-	-__-	40.4__-__-
Damaged Trees	31__-__-	-__-	59.6__-__-
Multiple Damage	-__3__-	9.7__-	-__5.8__-
Single Damage	-__28__-	90.3__-	-__53.8__-
Fork	-__-__14	-__45.2	-__-__26.9
Crook, 2 in.	-__-__8	-__25.8	-__-__15.4
Crook, 4-in.	-__-__5	-__16.1	-__-__9.6
Posthorn, 6-in.	-__-__1	-__3.2	-__-__1.9
Total	52__31__28	100.0__90.3	100.0__59.6__53.8
Data from every 5th tree every 5th row on ca. 1/2 acre
Undamaged Trees	8___-___-		38.1__-__-
Damaged Trees	13__-__-		38.1__-__-
Multiple Damage	-__2__-	15.4__-	-__9.5__-
Single Damage	-__11__-	84.6__-	-__52.4__-
Fork	-__-__4	-__30.8	-__-__19.1
Crook, 2-in.	-__-__5	-__38.5	-__-__23.8
Crook, 4-in.	-__-__2	-__15.4	-__-__9.5
Posthorn, 6-in.	-__-__-	-__-	-__-__0
Total	21___13___11	100.0__84.7	100.0__61.9__52.4

(40 percent of 52 trees on 1/10 acre). These data compare favorably with the 5th tree/5th row cruise data. Of the damaged trees, 90 percent were injured only once (Table 4). Most of this injury is correctable by pruning and 'crooks' of 2 inches or less are not a serious pulpwood defect; injuries of this type account for 71 percent of the singly-damaged trees.

Figure 8. -- A 40-year old plantation (III) near New Britain, Connecticut. This stand has been infested by the shoot moth for the past 26 years, yet little damage has occurred.

Figure 9. -- Thinnings from Plantation III. These 4-foot pulp sticks were cut to a 3-inch top and will be sold by the ton. Note shoot moth damage to red pine behind the pile.

Cull deductions are based on local merchantability standards. In this area, thinnings can be sold in 4-foot sticks, to a 3-inch top, by the ton (Figure 9). Thus if all damaged trees were sold in the next thinning and all forks and crooks less than 2 inches are not culled, then a total of 7 4-foot sticks will be lost (crooks greater than 4 inches). A good jobber could reduce this amount. After this thinning, the stand would consist of approximately 210 trees per acre with no shoot moth damage in the first 40 feet.

Plantation II

Figure 6. -- Plantation II. The mean annual height growth and branches per whorl of a red pine plantation infested with the European pine shoot moth since planting, also showing percent of injury by years. Bar graph percnet of injury; zig-zag line, mean annual branches per whorl, ascending line, height growth in feet. Horizontal axis years 1910 to 1960; vertical scale height in feet 0 to 30

The second plantation is located at the south end of the Saltonstal1 Division, Eli Whitney Forest, and to the east of the reservoir lying north of East Haven, Connecticut (Figure 5). It was not possible to determine if this stand was studied by Friend and West (1933).

A total of five trees were felled and measured. Data were obtained on defect resulting from shoot moth attack, number of branches per whorl, and internodal distance. The mean annual height and mean annual number of branches per whorl have been plotted (Figure 6). This plantation was infested within a few years after planting. Serious damage occurred in the early 1930's and again in the midl940's. Currently infested buds were found in the upper crowns.

Damage to this plantation was determined by examining every 5th tree in every 5th row for a total of 46 trees. This is approximately an 0.80-acre plot. Shoot moth damage was classified as in Plantation I: by fork, crook, and posthorn, also to the nearest foot above ground.

The spacing in this plantation is 6 x 6 and although some past cutting is evident, the stand does not appear to have been thinned. The mean total height is 33.2 feet and the trees were approximately 34 years old at the end of the 1958 growing season (based on a ring count at ground level). The site index is VII (Spurr, 1955), fair Rudolph, 1950), and 50 (Eyre and Zehngraff, 1948).

On this plot 76 percent of the trees have been damaged. The undamaged trees are well distributed and as yet the shoot moth has not affected what could be the final sawlog crop of approxi-mate1y 238 trees per acre (23.9 percent of 46 trees on an 0.80 acre plot). This data compares favorably with Plantation I, with 210 undamaged trees per acre.

In Plantation II multiple damage per tree was evident, 26 per-cent of all damaged trees were hit at least twice. Injuries such am forks are correctable by pruning and crooks of less than 2 inches are not considered a serious pulpwood defect; these injuries account for 63 percent of all damaged trees (Table 5).

Table 5a.Types and amount of damage to Plantation II caused by the European pine shoot moth. Based on a 46-tree sample.
	nbsp;	Types and Amount of Damage in 4-ft Sticks
Ht. Above Ground in feet		Fork	Crook<2in	Crook<4in	Post >4in.	Total	Percent
1.0-5.5	<1934	1	6	4	-	11	24.4
5.5-9.5	1934-1937	-	1	-	-	1	2.2
9.5-13.5	1937-1940	1	1	1	1	4	8.9
13.5-17.5	1940-1942	4	-	1	1	6	13.3
17.5-21.5	1942-1945	12	<-/TD>	<-/TD>	<3/TD>	<15/TD>	33.3
21.51-25.5	1945-1950	1	-	-	2	3	6.7
25.5-29.5	1950-1954	1	-	-	1	2	4.4
29.5-33.5	1954-1958	-	1	-	2	3	6.7
Total		20	9	6	10	45	99.9

¹Date above this height are above the minimum 3-inch top, as of 1958.
Table 5b.--Damage to individual trees and to the stand by the European pine shoot moth in Plantation II. Based on a 46-tree sample. Type of Damage Number of
Trees on Plot Damage Percent of Damaged Trees of the Plot Undamaged Trees 11         23.9     Damaged Trees 35         76.1     Multiple Damage   9   25.7     19.6   Fork and Crook >2-in.     6   17.1     13.0 >2-in. Crook and
Posthorn     2   5.7     4.4 Crook >4-in.     1   2.9     2.2 Single Damage   26   74.3     56.5   Fork     14   40.0     30.4 Crook <2-in.     2   5.7     4.4 Crook >4-in.     2   5.7     4.4 Posthorn >6-in.     8   22.8     17.4 Total 46 35 35 100.0 99.9 100.0 76.1 76.2

Cull deductions are based on 4-foot sticks to a 3-inch top. If forks and greater than 2 inch crooks are not culled, then the loss will be 16 four-foot pulp sticks in the first thinning (crooks greater than 2 inches and posthorns) if all damaged trees are cut (Table 5).

Plantation III

Figure 7. -- Plantation III. the mean annual height growth and branches per whorl of a red pine plantation near New Britain, Conn. infested with the European pine shoot moth since 1933. Ascending line is height growth in feet; zigzag line is mean annual branches per whorl.

This plantation is located on the Shuttle Meadow Reservoir near NewBritain, Connecticut (Figure 8). Data was obtained from five trees (felled in a going pulp job) as to internodal growth and branches per whorl. The mean height growth and branches per whorl have been plotted (Figure 7). Although this stand has been infested since 1935, damage has resulted in no merchantable losses. The few minor crooks and forks that were observed were not sufficient to warrant a cruise.

Reductions in the branches per whorl occurred in the mid-1930's, early 1940's, and the mid-1950's. Also currently infested buds were found in the crowns.

This plantation was planted at a 6 x 6 spacing and the mean height is 46 feet. The site index is IV (Spurr, 1955), 60 (Eyre and Veehngraff, 1948) and average (Rudolf, 1950). Thinnings were being sold in 4-foot sticks, to a 3-inch top, by the ton (Figure 9).

Plantation IV

Figure 10. -- The mean annual height growth and branches per whorl of two areas in a red pine plantation near New Britain, Conn, infested since planting, with the European pine shoot moth. Top graph is of height growth, lower one of branches per whorl. Upper line is fast growing trees, lower line is of slow-growing trees.

Figure 11 - A 13 year-old plantation (IV) on shallow soils near New Britain, Connecticut. These trees have been infested with the shoot moth since planting.The faster growing trees (right) have not been as severely damaged as the slower growing trees (left).

These 16-year-old trees are located on the Shuttle Meadow Reservoir near New Britain, Connecticut (Figure 11). The plantation was established in 1945 and immediately became infested by the shoot moth. In this stand there are fast and slow growing areas; data obtained in each area as to internodal growth and branches per whorl. This data has been plotted (Figure 10). The branches per whorl indicate severe attack in the mid-1940's and again in the mid-1950's.