Photo: 'Starking Delicious' pear tree. Inset: Pear preserves- 1) Starking Delicious, 2) Michigan 437, 3) Kieffer, 4) Orient, 5) Carrick.
University of Georgia
College of Agricultural Experiment Stations
O.C. Aderhold, President
Robert C. Anderson, Vice President for Research
C.C. Murray, Dean and Coordinator
John H. Owen, Director
Kenneth Treanor, Assistant Director
W.T. Fullilove Georgia Station, Experiment
Frank P. King Coastal Plain Station, Tifton
E. Broadus Browne College Station, Athens
Editor, Sam Burgess
DISEASE RESISTANCE AND ADAPTABILITY...5
SUMMARY AND CONCLUSIONS..............14
Evaluation of Pear Varieties for Georgia
B. O. Fry and E. K. Heaton
Associate Horticulturist and Associate Food Scientist, respectively, University of Georgia College of Agriculture Experiment Stations, Georgia Station, Experiment, Ga.
New pear seedlings constantly are being developed and introduced as varieties by breeders throughout the country. A large number of these have been grown and evaluated at the
Georgia Experiment Station for resistance to fire blight (Erwinia amylovora) and leaf spot (Fabraca maculata), the two most devastating diseases of pears in Georgia. Also, evaluations of processing qualities were made of fruit of several varieties in
these plantings. Most of the selections tested were those developed by breeders located in the South; however, other promising varieties or seedlings were included in the plantings. The purpose of this research was to provide information on the performance of these pear seedlings and varieties in the Piedmont area of Georgia. The data presented in this publication are results of trials at Experiment extending over the period from 1945 through 1965.
DISEASE RESISTANCE AND ADAPTABILITY
The first planting was set February, 1945, in four replicates of two plants each. Plants were spaced 30 feet apart in rows 25 feet wide. The planting consisted of five varieties and eight seedlings as shown in Table 1. The land was clean cultivated during the summer and followed with a rye cover crop during
the winter and early spring. The rye was harrowed down in early spring when it began competing with the pear seedlings
for nutrients and water. The newly-set trees were fertilized in March of the first year with one-half pound of an 8-8—8 fertilizer
per tree. In the second and third years, this fertilizer was increased to one and two pounds, respectively, per plant. The bearing
trees received from three to four pounds per tree in March of each year, depending on previous tree response. Pruning consisted of removing all diseased, injured, and crowding limbs.
Fire blight data were obtained at time of bloom and again in late summer. This information was secured by observing the per cent of infected blooms and shoot growth of the varieties
and seedlings in the plantings. Leaf spot records were obtained during early September by observing the severity of leaf drop caused by this disease. When a new seedling being tested failed
to rate as high as Kieffer in fire blight and leaf spot resistance, it was considered unworthy of recommendation.
The second planting was made during January, 1947, and consisted of the Baldwin, Kieffer, Harper, Lincoln, Richard Peters, Waite, Orient, and Walker varieties. Starking Delicious was added in 1953 and Michigan 437 in 1955. Plants were set in four replicates of four plants each, spaced 30 feet apart in rows 25 feet wide. Cultural practices and procedures of obtaining disease data were similar to those in the first planting.
The third planting was made during March, 1957, and consisted of the following varieties: Michigan 437, Richard Peters, Starking Delicious, Waite, Tennessee 34S3, and Orient. The varieties Morgan and Carrick were added in 1958; DeVoe, Bear Creek, and Russett in 1960, and Magness and Moonglow in 1962. Plants were set in one replicate of two plants each, spaced 25 by
30 feet apart.
Fertilization and pruning were similar to the first two plantings. Clean cultivation was practiced during the summer and a late weed growth was allowed to form a cover during the winter. No insect or disease spray programs were followed in either of the plantings. Disease data were obtained as in the first two plantings.
The Kieffer has been the, most extensively grown pear in the South and was used in the first two plantings as the basis for comparison of other seedlings and varieties in the studies.
Table 1 gives the rating of the different varieties and seedlings in resistance to fire blight and leaf spot diseases and the plant vigor of each over a 12-year period. There were several seedlings and varieties in the test that were rated superior to Kieffer in fire blight resistance, but they were considered unacceptable because of either small fruit, poor quality, or low yields. Two seedlings — Tennessee 34S99 and USDA 64224 —— were rated superior to Kieffer in fire blight and leaf spot resistance, but these were omitted in later plantings because of poor fruit quality.
Table 1. Evaluation1 of Pear Varieties and Seedlings, Experiment Georgia, 1945-57.
|Variety||Fire blighta||Leaf spot ||Plant Vigor|
|Tennessee 34S844 ||8.0||4.7||7.4|
10-Least acceptable score to 10-most acceptable
aBlossom and shoot evaluation
Four varieties selected from the first planting and four new ones were included in the 1947 planting (Table 2). All of the varieties in the test, except Lincoln, which was added because of its good fruit quality, and Kieffer, which was used as a basis of comparison, were thought to have considerable fire blight resistance. The most resistant varieties were Harper, Orient, Walker, Waite, and Richard Peters. These were found to be practically free of blight during the period of this test. Resistance to fire blight and leaf spot was essentially the same in the varieties included in both plantings. The Orient and Walker varieties rated highest in leaf spot resistance and Kieffer and Orient in plant vigor (Table 2).
Table 2. Evaluation1 of Pear Varieties, Experiment, Georgia, 1947-57.
|Variety||Fire blighta||Leaf spot ||Plant Vigor|
|Baldwin ||9.1|| 6.9 ||8.3|
|Harper ||10.0|| ||7.1 ||6.6|
|Lincoln ||6.9|| ||7.0 ||6.7|
|Richard Peters ||9.5|| ||7.8 ||7.4|
|Waite ||9.6|| ||8.2 ||7.0|
|Orient ||10.0|| ||9.3 ||8.6|
|Walker ||9.6|| ||9.0 ||8.0|
11 least and 10 most acceptable score
aBlossum and shoot evaluation
The Kieffer variety was not included in the 1957 planting because of frequent frost injury to blossoms and its poor fruit quality. The varieties set in this planting were found to be highly resistant to fire blight under conditions at Experiment (Table 3). However, a spray program for the control of leaf spot would be required most years for best results (Figure 1). The plant vigor of each variety in the planting was found to be satisfactory with Starking Delicious and Waite showing the least vigor.
Table 3. Evaluation1 of Pear Varieties, Experiment, Georgia, 1957-65.
The Magness and Moonglow varieties have not been in the planting at Experiment a sufficient number of years to obtain conclusive results of their performance in this area. The blooming
date is usually 10 days later than Morgan at Experiment, Georgia.
|Variety||Fire blightb||Leaf spot ||Plant Vigor|
|Michigan 437|| 9.8|| 9.0|| 10.0|
|Starking Delicious|| 9.3|| 8.0|| 5.8|
|Waite|| 9.4|| 7.7|| 6.5|
|Orient|| 9.5|| 6.2|| 8.5|
|Morgan|| 9.8|| 9.0|| 7.1|
|Carrick|| 9.6|| 6.7|| 6.5|
|Magnessa|| 10.0|| 10.0|| 8.1|
|Moonglowa|| 10.0|| 7.7|| 8.9|
|Bear Creek|| 9.1|| 4.6|| 8.1|
|Russett|| 9.3|| 7.0|| 9.2|
110 most acceptable
aPlants set in 1962
bBlossom and shoot evaluation
The blooming date of pear varieties in the South is an important factor in fruit production. Temperature data (Table 4) obtained at Experiment, Georgia, during the past 14 years show that below freezing temperatures have occurred each year during April except in 1954 and 1965. However, frost did not occur at Experiment all of e years in which the temperature dropped to 32°F. or below. Therefore, the selection of late blooming varieties is important for plantings in the Piedmont area of Georgia. In most years of the test, the early blooming of Baldwin, Kieffer, and Harper (Table 5) usually resulted in frost injury to the blooms and low fruit yields for this period. It may be noted (Table 5) that many of the recently introduced varieties such as Orient, Michigan 437, Morgan, Starking Delicious, and Carrick did not bloom until well after Baldwin and Kieffer. These late-blooming varieties have a much better chance of escaping frost injury during the blooming period than those that bloom early. Waite and Richard Peters seldom set a good crop of fruit at Experiment regardless of weather conditions.
Table 4. Minimum Temperatures During April 1952-65, Experiment, Georgia.
|Year ||April [date] ||Temperature (°F)|
The Magness pear is self-sterile and requires a second variety for cross-pollination. Self-sterile varieties make it necessary to plant other varieties with comparable blooming periods. Bloom dates of several varieties are shown in Table 5.
The varieties Kieffer, Orient, and Morgan are usually the larger fruited varieties as indicated in Table 5. The varieties Walker and Harper have very small fruit and are not considered good for processing.
Table 5. Blooming Dates, Ripening Dates, and Fruit Size of Several Pear Varieties and Seedlings, Experiment, Georgia, 1950-65.
|Variety||Dates full blooma||Average ripening date||Fruit sizeb|
|Baldwin||2-3 to 3-2|| 8-22||8|
|Kieffer||2-17 to 3-18 ||9-3||10|
|Walker||3-11 to 3-20 ||9-1||4|
|Harper||2-21 to 3-4 ||9—4||5|
|Waite||3-14 to 3-24 ||8-20||8|
|Starking Delicious||3-14 to 4—14 ||8-7||8|
|Michigan 437 ||4-4 to 4—15 ||8-4||8|
|Orient ||3-8 to 4-8 ||8-9||10|
|Morgan ||3-13 to 4-15||8-16||9|
|Carrick ||3-4 to 4-12||8-24||7|
aThe earliest and latest blooming date during this test
bComparative fruit size: 5- medium to 10-large
The pears grown in Georgia are used chiefly for preserving and canning. They also are excellent as spiced or pickled pears, pear sauce, frozen pears, and pear relish. The most suitable pears for processing are those grown on vigorous, healthy trees. Characteristics which make pears desirable for processing include:
(1) uniformity of size, shape, color, and maturity; (2) fine texture without grit cells; and (3) freedom from insects, diseases, and blemishes. Pears are superior for processing when picked
six to eight days before optimum maturity and ripened at 70 to 75°F.
Six varieties were evaluated for canning and preserving in 1953 and nine varieties were evaluated in 1965. After harvesting, the pears were graded according to ripeness. The ripe fruit was processed on the same day, and the green fruit was ripened at 70°F. and 80 per cent relative humidity until ready for processing. The pears were peeled in a 10 per cent lye solution, washed, cut in halves and cored by hand. (Pears oxidize and turn brown very rapidly after peeling, and if they are to be held for more than a few minutes, they should be covered with dilute, 1-2 per cent, salt brine.)
For canning, the peeled and cored halves were filled cold into No. 2½ cans, covered with boiling 30 per cent soluble solid syrup and sealed. The cans were cooked in boiling water for 25 minutes and cooled in running water.
Table 6. Processing Yield of Pears, Experiment, Georgia, 1953.
|Yield of finished product|
|Variety||Fruit (pounds)||Prepared fruit (%) ||canned (pints)||preserved (10-oz. jars)||Suitability|
| canned||29||66.2||21||very good|
| preserves ||28||66.2||29||very good|
| canned||23||68.0||16||very good|
| preserves||23||68.0||27||very good|
Quality in canned pears depends largely upon variety, optimum maturity, careful grading, and proper ripening temperature.
In these studies Michigan 437, Orient, Carrick, Waite, and Starking Delicious were considered superior to Kieffer for canning (Table 7). Michigan 437, Carrick, and Starking Delicious were smooth and easy to peel with lye, had small cores and fairly fine texture with few grit cells. They produced a higher than average yield of prepared fruit and made attractive canned halves. Waite and Moonglow were rated somewhat higher than Kieffer. The Waite had large grit cells, slightly yellow color and weak flavor; the Moonglow was ragged and soft with moderately smooth texture and good aroma and flavor. Morgan and Tennessee 34S3 were about equal to Kieffer for canning. The Morgan had brown corky spots which detracted from the overall
quality. This corky condition was believed to be caused by either disease or a nutritional deficiency. This variety had weak aroma and flavor. The Kieffer and Tennessee 34S3 were of similar
quality when canned, having many grit cells and lacking aroma and flavor.
Table 7. Suitability of Pears for Canning, Based on Processing Characteristics and Sensory Evalautions, Experiment, Georgia, 1965.
|Variety ||Suitability ||Comments|
|Michigan 437||very good||Smooth, white, tender, with few grit cells. good flavor.|
|Carrick||good||Smooth, s1ightly pink, firm, required longer cooking time.|
|Orient||good||Irregular size, good sheen, several grit cells, good flavor.|
|Starking Delicious||good||Large, irregular shaped fruit, white, firm with few grit cells, good flavor.|
|Waite||fair||Large, s1ightly yellow colored fruit. large grit cells, flavor fair.|
|Moonglow||fair||slightly ragged, light cream colored, soft, smooth, good aroma and ﬂavor.|
|Morgan||poor||Soft, ragged, medium yellow with “disease or deficiency" spots, lacking aroma and ﬂavor.|
|Kieffer||poor||Firm, slightly pink fruit with many grit cells, lacking aroma and flavor.|
|Tennessee 34S3||poor||Firm, slightly pink, many grit cells, lacking pear ﬂavor.|
The pinkish color, fruity flavor, and pleasing consistency of pear preserves make them one of the most popular preserves.
The preserves were made according to the following formula:
|Prepared fruit, sliced ⅛-inch thick||10 pounds|
|Citric Acid||⅓ ounce|
Water and sliced fruit were mixed and boiled for 10 minutes, then the sugar and citric acid were added. The mixture was boiled briskly, until the temperature reached 221°F., about an hour. After preserves had finished cooking, the heat was out off, and gentle stirring was continued until the temperature dropped to 190°F. This permitted air bubbles (foam) to rise to the surface and he skimmed off. This also helped to prevent floating of the fruit. The preserves were filled into preheated jars, sealed and inverted for four minutes, which allowed time to sterilize the lids. The jars were set upright and cooled in water.
All varieties of pears tested made acceptable preserves (Tables 6, 8). Based on processing and quality characteristics, four of the
10 varieties were considered very good, two good, and four fair for preserves (See Cover). Those considered best were: Michigan 437, Carrick, Starking Delicious and Baldwin. Orient and Waite
rated good, and Moonglow, Morgan, Kieffer, and Tennessee 34S3 rated fair.
In preserves made from Michigan 437, Carrick, Waite, Kieffer, and Tennessee 34S3, the fruit retained its shape well and had very
attractive appearance. In Moonglow, Morgan, and Orient, the fruit became soft and fragmented, and failed to develop a pronounced pink color during cooking. Preserves made from the
Moonglow variety had a soft texture and mild flavor and Starking Delicious had a slightly tough texture with good flavor. Kieffer
and Tennessee 34S3 had many large grit cells and lacked flavor.
The Orient, Moonglow, and Morgan made preserves with pale color. (Where pink color is desired, food coloring may be added to varieties which fail to develop pink.)
Table 8. Suitability of Pears for Preserves, Based on Processing Characteristics and Sensory Evaluations.
|Michigan 437||very good||Fruit distinct, glossy, and slightly chewy with good flavor.|
|Carrick||very good||Similar to Michigan 437 except slightly weaker flavor.|
|Orient||good||Pale, light pink color, fruit soft with grit cells, lacking flavor.|
|Starking Delicious ||very good||Fruit fragmented, very red, gritty, and slightly tough, with good flavor.|
|Waite||good||Fruit distinct and glossy, “chewy” with some grit cells, and weak flavor.|
|Moonglow||fair||Fruit fragmented, pale color, soft with many grit cells, lacks ﬂavor.|
|Morgan||fair||Fruit fragmented, color very light, mealy texture and good flavor.|
|'Kieffer'||fair||Fruit distinct with uneven, dark red color, grainy with many large grit cells, and caramelized flavor.|
|Tennessee 34S3||fair||Fruit looks grainy, glossy, and was tough with large grit cells, and lacked ﬂavor.|
SUMMARY AND CONCLUSIONS
The Kieffer pear grown under Southern conditions tends to fire blight severely making it an undesirable variety for the grower.
The varieties which have shown the greatest degree of fire blight
resistance over a period of several test years are Morgan, Michigan 437, Carrick, Orient, and Waite. No spray program is recommended for the control of fire blight. Magness and Moonglow were set in the planting in 1962; therefore, no conclusive results on fire blight resistance have been obtained.
The Orient, Michigan 437, Morgan, Starking Delicious, and Carrick are late blooming varieties and stand a better chance of escaping frost injury than those varieties that bloom early.
The Kieffer and Orient varieties produce the largest fruit and Waite, Starking Delicious, and Michigan 437 produce a medium-size fruit.
Michigan 437, Carrick, Starking Delicious, and Orient are considered the best varieties for preserving. Orient produces a light
colored preserve, but color may be added if desired.
Michigan 437, Carrick, Orient, and Starking Delicious are the better canning varieties. The Kieffer is the leading variety grown
in the South, but it contains large grit cells and is not considered
good for either preserving or canning.
Since some pear varieties are self-sterile, cross-pollination
with other varieties should be provided to insure a set of fruit.
The varieties Morgan, Carrick, Orient, Kieffer, Starking Delicious, and Michigan 437 usually set a crop of fruit when planted alone;
however, highest yields are obtained when two or more varieties
are set in the same planting. The Magness pear requires a second variety for cross-pollination.