tattering of leaves from wind, mining associated with webbingfrom an unrecovered insect, and feeding at internodes (Figure 1

On a tree by tree basis, tree number 3 had more symptoms andorganisms on leaves than the other trees (Table 2) .Pear thripsoviposition scars were present on more leaves than any othersymptom or organism, and by later collections, high numbers ofoviposition sites were recorded (Table 3) .

The other most frequent symptoms or organisms present were: mapleleaf cutter feeding, leaf hopper feeding, necrotic feeding atinternodes and purple mottling apparently caused from hot, dryweather. One unique occurrence was that leathery leaves occurredon the 3 last collection periods on tree 5, only. Tree 5 alsowas the only tree to have single occurrences of Aceria regulus,eyespot (Phvllosticta minima) and a birch leaf miner larva.

Although this study is not designed to determine the impact onleaves from the different damage agents, general comments on thecondition of leaves in 1991 may assist in comparing years. Theleaves collected in 1991 were generally healthy. Little majordefoliation was present. Light defoliation from maple leafcutter was present on lower foliage of the sample trees, but thisdid not extend up into the mid-canopy leaves. Overall damagefrom pear thrips was considered very light to none.

Our initial intent in this study was to survey sugar maple leafdiseases. Due to unusually dry conditions early in the growingseason, few diseases were present, but many other damage agentswere. We therefore expanded our survey to better represent trueleaf conditions, including all symptoms and organisms present.

Fundinq Sources

Funding was provided, in part, from a USDA Forest Service grantfor Vermont Monitoring Cooperative activities and USDA ForestService Forest Health Protection funds for accelerated forestpest detection activities.

Future Plans

In 1992, we plan to expand this study to include 2 additionaltree species and one additional site at a higher elevation (2200ft) on Mt. Mansfield.

32

Figure 1. Disease symptom present on sugar maple leavescollected from Proctor Maple Research Center, 1360 ft. (415 m),on Mount Mansfield, Vermont.

Figure 2. Internodal insect feeding present on sugar mapleleaves collected from Proctor Maple Research Center, 1360 ft.(415 m), on Mount Mansfield, Vermont. No causal agent was

recovered.

33

Table 1. Symptoms and organisms present on sugar maple leavescollected on five dates in 1991 from mature, codominant sugarmaple trees at the Proctor Maple Research Center [1360 ft (415m)], Mt. Mansfield, VT.

THREE MOST COMMONSYMPTOMS AND ORGANISMS

% OF LEAVES WITH

DAMAGE OR ORGANISMDATE

149 MAPLE LEAF CUTTERPEAR THRIPS EGG SCARSWIND TATTERING

554831

165 MAPLE LEAF CUTTERPEAR THRIPS EGG SCARSWEBBING INSECT FEEDING

757265

177 PEAR THRIPS EGG SCARSLEAF HOPPER FEEDINGMAPLE LEAF CUTTER

916858

193 PEAR THRIPS EGG SCARSLEAF HOPPER FEEDINGNECROTIC INTERNODES

937157

220 PEAR THRIPS EGG SCARSNECROTIC INTERNODESLEAF HOPPER FEEDING

948884

34

Table 2. Symptoms and organisms present on sugar maple leavescollected from 5 different sugar maple trees growing at theProctor Maple Research Center [1360 ft (415 m)], Mt. Mansfield,VT.

5 MOST COMMON SYMPTOMSOR ORGANISMS PRESENT

% OF LEAVES WITH

DAMAGE OR ORGANISMITREE NO.

1 6656514135

PEAR THRIPS EGG SCARSMAPLE LEAF CUTTERLEAF HOPPER FEEDINGDISEASE SYMPTOM (Figure 2)WIND TATTERING

2 7571694240

PEAR THRIPS EGG SCARSLEAF HOPPER FEEDINGMAPLE LEAF CUTTERDISEASE SYMPTOM (Figure 2)INTERNODAL INSECT FEEDING (Figure 1

3 8771584743

PEAR THRIPS EGG SCARSLEAF HOPPER FEEDINGPURPLE MOTTLINGMAPLE LEAF CUTTERINTERNODAL INSECT FEEDING (Figure 1

4 8275666334

PEAR THRIPS EGG SCARSMAPLE LEAF CUTTERINTERNODAL INSECT FEEDING (Figure 1)LEAF HOPPER FEEDINGRASPING INSECT FEEDING

8873696054

5 PEAR THRIPS EGG SCARSINTERNODAL INSECT FEEDING (Figure 1MAPLE LEAF CUTTERLEATHERY LEAVESLEAF HOPPER FEEDING

35

Table 3. Frequency of pear thrips oviposition on sugar mapleleaves collected over the spring and summer, 1991, Proctor MapleResearch Center [1360 ft (415 m)], Mount Mansfield, Vermont.

Julian date Ave. No. Egg Scars/Leaf

149165177193220

1.483.885.336.645.68

36