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Vegetable Improvement Newsletter No. 5, February 1963
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Compiled by D.H. Wallace, Cornell University, Ithaca, New York

1. Nematode Resistance in Phaseolus

Paul G. Smith and Adrian Gentile

Department of Vegetable Crops, University of California, Davis

The last report on nematode resistance in beans (Phaseolus vulgaris) was published in 1939 by Barrons (Jour. Agr. Res. 58:263:72). He postulated resistance found in the variety Alabama #1 to be due to the interaction of two recessive genes. In view of the recent taxonomic revision of the root-knot nematodes, one variety of Phaseolus coccineus and 56 varieties of P. vulgaris, including the Alabama #1 used by Barrons, were tested for resistance to Meloidogyne incognita, and 15 varieties of bean and one variety of Vigna sinensis (Blackeye #5) were tested for resistance to M. javanica and M. hapla. All. were susceptible to the latter two nematode species, although line 11(43)56, Isabell's Nematode Resistant (PC 51644), and Blackeye #5 were resistant to M. incognita.

Sixteen lines showed moderate to high resistance to M. incognita, but none was immune. A few small galls, often with females and egg masses, and light to severe root necrosis were observed. Some variation was seen in severity of root necrosis and in numbers of developed females, but it remains to be determined whether this represents variation in degree of resistance or in inoculation technique. Phaseolus coccineus (Scarlet Runner) was also highly resistant.

Seven varieties had an abundance of females and egg masses, but very little gall formation. These, while classes as susceptible, probably are capable of reasonable growth in infested soil.

The remainder were highly susceptible, showing typical large galls and extensive root decay. A restudy of the inheritance of resistance is under way.

More detailed information on the varieties tested and their responses, is available to anyone interested.

2. Nature of Cabbage Downy Mildew Resistance

W. R. Sitterly

Clemson College Truck Experiment Station, Charleston, South Carolina

Upon histological examination of the downy mildew susceptible variety, Round Dutch, and the downy mildew resistant PI 261769 and PI 261774 cabbage lines, the following information was noted:

On leaves of susceptible Round Dutch, sporulation was intense. Mycelium ramified throughout the leaf intercellularly with haustoria intracellularly. Chloroplasts faded and cell contents clustered in one large ball in the cell. Collapsed cell areas became dark and carbonaceous.

On leaves of the resistant PI 261769 and PI 261774, tissues did become infected, but sporulation was very sparse. Mycelium grows slowly in the host, but never does stop growing. Internal position of the mycelium with regard to host cells is the same as for susceptible leaves, but fungus effect is not so pronounced so far ahead of the mycelium, and chlorophyll is not destroyed as rapidly.

Although resistance is not expressed as a hypersensitive reaction, the sparse sporulation and the considerably reduced pace of the fungus life cycle does allow classifying these PI lines as having good resistance to cabbage downy mildew.

3. Severe Effects of Cucumber Mosaic Virus on Cucumber

Joseph Prend

Crop Research Department, H. J. Heinz Company, Pittsburgh, Pa.

About July 15 very early plantings of Ohio MR17 AND Wis. SMR 12 cucumber made in an area surrounded by many perennial weed hosts began to exhibit severe yellowing of vines. Plants began to die shortly thereafter and all were entirely dead by about September 1. Soil borne wilts were suspected but plating of roots by Dr. James Strobel of the University of Florida indicated that no organism was present. No leaf nor stem lesions were observed but many fruit showed cucumber virus symptoms. A similar occurrence was recorded in Bulgaria in 1961.

4. Gummy Stem Blight (Black Rot) of Cucurbits

W. C. Barnes and W. R. Sitterly

Clemson College Truck Experiment Station, Charleston, South Carolina

Gummy stem blight is either becoming more of a problem in cucurbits in the South or with the introduction of varieties resistant to other diseases the damage carried by this pathogen has become more apparent. Many growers have reduced the rotation period which accentuates the problem of soil carry over. Volunteer plants are another source of spores.

In the past no cucurbit variety was considered as having resistance to this disease. With the introduction of PI 197087 in the South Carolina breeding program it became evident this accession carried greater susceptibility to gummy stem than had been observed in previous material. In spite of efforts to select against this greater susceptibility Polaris is slightly more susceptible than varieties such as Ashley. Some new lines that will be ready for testing in 1964 apparently are no more susceptible than Ashley. Anyone using 197087 or material derived there from should watch carefully for this undesirable characteristic.

5. Field Selection of Verticillium-Wilt Resistant Eggplant

John Wiebe

Horticulture Experiment Station Vineland Station, Ontario

Eggplant is only a very minor horticultural crop but has been profitable for a few growers. Verticillium wilt of eggplant is widespread and serious in all of
Southern Ontario. In 1956 a program was started to develop a wilt-resistant variety. Resistant lines were obtained from the U.S.D.A. Plant Introduction Service. PI lines that proved most useful over the years were: PI 214177, PI 222269, and PI 222833. These lines had small, oblong to long, green fruit. There was a considerable variability within the lines in their susceptibility to Verticillium. The most resistant (or tolerant) plants were crossed with Black Beauty. The F1 was intermediate in resistance. It was easy to obtain purple-fruited lines. These lines have been backcrossed to Black Beauty one and two more times. Selections were made in each generation for resistance and/or desirable horticultural characteristics.

A number of fairly uniform purple-fruited lines with a fair level of resistance now are available. We expect to backcross several more times in order to obtain the fruit characteristics of Black Beauty.

Temperature tank inoculation of seedlings might speed the selection. However, there are some indications that results obtained this way may not parallel field selection. Our method had been to plant in a field which has had tomatoes and eggplant in it repeatedly. Final selections are made at the end of the growing season.

Breeders wishing to use this material may have small amounts of seed on request.

6. A Gene For Depth Of Corolla Cleft In The Lettuce Flower

Edward J. Ryder

U. S. Agricultural Research Station, Salinas, California

The ligulate corolla of the lettuce (Lactuca sativa L.) flower is 5-toothed at the apex. The cleft between the teeth can be classified as deep or shallow and is characteristic for a variety.

A cross was made between USDA 6911 and USDA 6943, two crisphead type breeding lines. Line 6911 has shallow clefts; it is also black seeded. Line 6943 is deep clefted and white seeded. At the time the cross was made, it was thought that 6943 was also male sterile, but this was apparently only a temporary condition marked by lack of pollen. It was used as the female parent and segregation of the seed color characteristic in F2 (white is recessive) proved that a successful cross was made.

The F1 had deep clefts. Segregation in F2 and F3 families from deep F2 plants was as follows:

A Gene For Depth of Corolla Cleft in the Lettuce Flower

 

Observed

Expected

Generation

Expected ratio

Deep

Shallow

Deep

Shallow

X2

Prob.

F2

3:1

83

25

81

27

.20

.50-.70

F3

1:2

4

7

3.7

7.3

.05

.80-.90

One additional F3 family bred true for shallow cleft, indicating a misreading of the F2 plant as deep.

The data indicate that deep cleft is dominant to shallow and a single gene accounts for the difference. It is therefore labeled Shsh.

Mather's* method was used to calculate linkage with the gene for seed coat color. Using F2 data, chi square for the 9:3:3:1 ratio was partitioned into three parts, two for the segregation of the respective characters and one for linkage. The test indicated no linkage.

*Mather, K. 1951. The measurement of linkage in heredity. Methuen, London.

7. Stem Doubling and Fasciation in Lakeland Head Lettuce

T.W. Tibbits

Department of Horticulture, University of Wisconsin, Madison

Under Wisconsin conditions, Lakeland head lettuce plants frequently develop two growing points during the heading stage which results in the production of soft puffy heads. When left to flower, both growing points develop stems of equal size.

The Lakeland variety also has a significant amount of stem fasciation. This occurs on both normal and double-stemmed plants. On the doubled plants, often one stem will fasciate and the other will not. Both normal stems and fasciated stems have been shown to produce normal flowers and mature seed. In a very small percentage of the plants the stem fasciates just as the head is forming. This also produces a very puffy head.

8. Green-Seeded Downy Mildew-Resistant Fordhook Lima Beans

R. E. Wester

U. S. D. A. Plant Industry Station, Beltsville, Maryland

Three new green-seeded downy mildew-resistant Fordhook lima beans (U. S. 561, 861, and 1061) showed considerable promise in Maryland, New Jersey, and Long Island in 1961 and 1962. They resisted downy mildew (Phytophthora phaseoli, Thaxt.) strain "A" which in some years causes considerable damage to lima beans in Maryland, Delaware, New Jersey, Pennsylvania, and New York. Their yields equaled or exceeded those of Fordhook 242. Plants of the new lines are slightly shorter and more compact than those of Fordhook 242 and have short racemes that produce a heavy crop of pods before the foliage, thus preventing flower drop which often results from excessive heat, drought, wind, and rain. Pods reach prime marketable condition 4 to 6 days later than Fordhook 242 and remain in this condition several days longer. The pods are approximately as long and thick as Fordhook 242 but not quite so wide. The shelled beans are slightly smaller than those of Fordhook 242 and darker green in frozen pack. the quality of the cooked beans is excellent.

9. Summer Squash Virus Complex

W. R. Sitterly

Clemson College Truck Experiment Station, Charleston, South Carolina

The purpose of our summer squash breeding programs to develop varieties resistant to squash mosaic virus, and possible cucumber mosaic virus. In 1961 and 1962, breeding lines supposedly resistant to SMV and CMV were developing more virus symptoms than was thought should occur - barring a complete loss of resistant germ plasm. Upon identification of numerous isolates by means of a standard set of cucurbit virus differentials, watermelon mosaic virus was also found to be present. Not only was this third virus present to confuse project goals, field identification of specific viruses is now uncertain. There was not only a wide range of symptom expression for a particular virus, there was also symptom duplication amongst the viruses involved. Field identification of virus mixtures in a host fall into the category of an "educated guess". Another variable has thus been introduced requiring an evaluation of the goals of this particular project.

10. Internode Length of Tomato Variety K.Y.1 and Its Behavior In A Cross With Red Tip VR 9

C. A. John

Crop Research Department, H. J. Heinz Company, Pittsburgh, Pa.

The Australian variety, K. Y. 1, is characterized by a compact bushy plant type with short internodes. Dr. L. Butler of the University of Toronto kindly studied the genetics of the short internode and indicated that this is due to the brachytic gene. It is indeterminate and bears a flattened fruit which matures rather early and has better foliage cover than most other early lines. As noted in the accompanying table, ten unselected plants, Red Top VR 9 averaged 1.9 inches in internode length. An F2 population of 91 plants was studied for internode length and plant type. It will be noted that regardless of whether the plants were determinate or indeterminate, the average internode length was 1.7 inches.

Table 1. Summary of Studies on Internode Length of K.Y.1, Red Top VR 9, and the F2Progeny of a Cross Involving These Two Varieties, Bowling Green, 1960.

Class

Internode Length in Inches

K.Y. 1

Red Top VR 9

Det. F2Pop.

Indet. F2Pop.

0.9 -1.1

0

0

1

1

1.2 - 1.4

5

1

8

13

1.5 - 1.7

5

3

8

18

1.8 - 2.0

0

2

10

23

2.1 - 2.3

0

2

1

1

 

 

 

 

 

TOTAL

10

10

30

61

 

 

 

 

 

Variety Average

1.5

1.9

1.7

1.7

11. Evaluation of Ease of Stem Removal From Tomatoes

E. A. Kerr

Horticultural Experiment Station Vineland Station, Ontario

In Ontario the stems must be removed from tomatoes sold for strained products. Growers, therefore, want varieties whose stems can be easily flicked off. In varieties for mechanical harvesting it is desirable that the stems remain on the plant or at least separate easily so that less damage will result from stem punctures. There also seems to be an association between the size of the core and the ease of removal of the stem.

In 1961 and 1962 an attempt was made to evaluate ease of stem removal. There was only a very low correlation between ease of stem removal and the number of stems remaining on the fruit when picked "with the stems on". Subsequently the stems of ten fruits per replication were flicked by drawing the thumb briskly across and back over the stem end of the fruit. Counts were then made of the stems that stayed on and converted to relative value by means of the formula.

Ease of stem removal = (5 x number of stems removed) / (total number of fruits)

This gave a rating of 0 to 5 with the higher ratings the more desirable. The following values are based on eight replications.

C 1327

1.4

H 1350

2.9

Rideau

4.0

C 135

2.3

Fireball

3.6

Glamour

4.1

C 1402

2.4

ES #24

3.4

C 52

4.9

Viceroy

2.6

Viscount

3.8

VF 145

5.0

L.S.D. 5 % =

0.88

 

 

This method of evaluation is subjective to considerable extent. However it is rapid and when the flickering is done by one person, it has separated varieties approximately in the expected order.

12. Marker Characters In Tomatoes

P. A. Young

Tomato Laboratory, Texas Agricultural Experiment Station, Jacksonville

It is nice to have a new tomato variety with a marker character for easy recognition of the variety in the field. This helps to keep the seeds pure. Luckily, Pinkdeal tomato has a new marker character. The green fruits, 1 to 2 inches in diameter, show dim lighter colored meridian stripes that disappear as the fruits ripen. They are unlike the marker character of Earliana variety that has dark green radiating stripes the blossom-end of the green fruits; sometimes these stripes remain visible in the ripe fruits.

Cherry tomatoes and some plum tomatoes commonly have unusually small leaflets by which they can be recognized; the small-leaflet character probably is polygenic.

White flowers make an excellent marker in tomatoes. They are described in Texas Agr. Exp. Station Bul. 698 on Horticultural Characters of Tomatoes. Selection T935 was selected through many generations to make a new variety but I was unable to eliminate one defect: the fruits averaged 3 to 4 oz. and thus they were too small for the market. T935 tomato has excellent resistance to catfacing. Although it is not good enough variety in its present form, maybe someone would like to use it in crosses to add this nice recessive marker to other kinds of tomatoes.

W1083 has two recessive markers: white flowers and some epinastic curling of leaflets in a genotype with large yields of big fruits. However, the vines are nearly prostrate so W1083 is not good enough for a new variety in its present condition. Maybe someone would like to cross it to transfer the white flower marker to other kinds of tomatoes.

Pearson tomato is marked by its extra dark green leaflets. It is excellent in western United States. Unfortunately it often shows another marker at the Tomato Laboratory at Jacksonville, Texas. The blossom-end of the little green fruits commonly protrudes. often with a sharp point. This character presumably is different from those due to the n and bk alleles. Also, it differs from Oxheart. I sent samples of such fruits to Dr. C. M. Rick at Davis, California and he replied that Pearson does not show this character there. The blossom-ends of Pearson fruits are usually rounded.

Golden Sphere tomato did not become popular probably because the ripe fruits burst in wet weather. This variety has two markers: smooth leaflets and characteristic seedlings.

13. Shiski-Bab Tomatoes

P. A. Young

Tomato Laboratory, Texas Agricultural Experiment Station, Jacksonville

Tomato breeders usually have discarded segregates with small fruits as they were assumed to be unmarketable. However, we now have two new markets for little tomatoes. For variety, little red cherry tomatoes are chosen instead of tree cherries in champagne glasses. Back yard grills and barbecue pits have become popular and with them, a good demand for red plum tomatoes for salads. A tomato buyer from the Lower Rio Grand Valley told me how to make a shiski-bab. Take the steel skewer and string onto it slices of bacon, onion rings, plum tomatoes, hot dogs, etc. and toast them over the grill. This makes fine eating. I have two kinds of tomatoes for shiski-babs.

The search for resistance to southern blight of tomato included a visit with a man who had recently returned from duty in the South Pacific area. He said that people there do not need to raise tomatoes. When someone wants tomatoes, he walks into the forest, finds a tomato plant about 4 ft. tall and 20 ft. long and picks off all the red cherry tomatoes that he wants. It took a year, but the USDA kindly imported a tomato like that for me to test; this is PI 190256, PQX18953 from Novelle Caledonia, New Hebrides Islands. I crossed it with S1119 hot setting tomato and tested the progeny for resistance to Sclerotium rolfsii, but found none. The 6-year search with field tests of of tomato species, varieties, and crosses including interspecific crosses showed no kind with more than about 10% resistance to Sclerotium rolfsii. However, the new hybrid cherry tomato (S1447) has outstanding virtues: The red fruits are 1/2 to 3/4 inch in diameter, very sweet, and thousands of them grow on very large vigorous plants; the fruits set abundantly in very warm weather.

The perennial search for immunity to tomato fruit cracking continues. This is not yet attained with large tomatoes but CP1627 red plum tomato has about 99% resistance to fruit cracking. It came from a cross of CP1362 x PI 134208 from India. The plants are very large with characteristic small dark green leaflets. The red plum fruits rarely crack even when over ripe on the plants in wet weather.

Would you like to buy cherry or plum tomatoes? They cost 35 cent per lb. in cellophane sacks or plum baskets in the supermarket.

14. Breeding for Field Resistance to Verticillium

C. C. Wyatt

Crop Research Department, H. J. Heinz Company, Pittsburgh, Pa.

Extreme infestations of verticillium wilt, Verticillium albo-atrum (Reinke and Berth), were observed in isolated tomato fields in northwestern Ohio and the Leamington, Canada area during 1962. Tomato fields planted with verticillium resistant varieties with the Ve gene were observed to maintain leaf turgidity throughout the day whereas entire fields of susceptible commercial varieties exhibited extreme wilting of young leaflets. The tomato varieties without the Ve gene also exhibited typical V-shaped lesions and chlorosis. Leaves on susceptible varieties would regain turgor during the evening, but wilting would soon occur following exposure to sunshine.

During 1961 and 1962 studies have been conducted in the greenhouse to determine the pathogenicity of various isolates of verticillium from plants selected from commercial fields in Ohio and from other sources. During 1961 and 1962 the pathogenicity of twelve different isolates was studies using the method suggested by O. Cannon and others. Reading for verticillium resistance were made using size of plant, leaf symptoms and by examination of the root by cutting with a razor blade. The variety VF 36, Cannon 10, H 1350, and VF 145 exhibited a very high level of resistance to the twelve isolates.

During the years 1958, 1959, and 1960 all lines with the Ve gen have exhibited a high level of resistance to verticillium isolates using the technique mentioned above. In screening breeding lines for Verticillium resistance in tomato it has seemed best to mix a number of separate isolates and this procedure has been successfully carried out for a number of years. From observations made in the field during 1962 it is apparent that a worthwhile level of resistance to verticillium can be obtained using varieties with the Ve gene in northwestern Ohio and the tomato production area that surrounds Leamington, Canada.

15. A Method For Reducing Air Temperatures of Flower Tissues Protected By Gelatin Capsules

O. H. Pearson

Seed Research Specialists, Hollister, California

Gelatin capsules of 00 size are convenient protectors for melon, cucumber, and pepper flowers in controlling pollination. However they are highly transparent, and allow no air movement, and tissue so protected when exposed to the sun may reach high enough temperatures to cause damage. As far as I know, now fully opaque kinds are available.

During this past season, in working with melons in the central valley of California, we were able to overcome this damage by dipping the capsules in aluminum paint. Stigmas covered by these aluminized capsules remained succulent for the full period after pollination, whereas those covered with clear or pink capsules rapidly burned. While we have no data for comparative sets with the same type of covering, it would seem that this would eliminate one variable the may influence success in handling this difficult crop.

16. A Method For Rearing Blow Flies For Pollination Purposes

O. H. Pearson

Seed Research Specialists, Hollister, California

The standard method of rearing blow flies on beef lungs and allowing them to pupate in sand has caused us difficulty in this region of low humidity. The emergence of the pupae has been well under 10%, and even less when pupae are introduced into small cages. A modification of the method used by the Shell Development group has given us excellent results.

Blow fly larvae are fed to full development on beef lungs in the open and are caught in sand trays placed under the lung trays. A quart mason jar is filled loosely with excelsior, and about half inch of water is added. A small handful of larvae is placed in the jar, and it is covered with a screw cap in which the tin lid has been replaced with a disc of 32 x 32 mesh plastic screen. The jar is kept at air temperature. The larvae pupate at about the mid point of the jar. The emerge all at about the same time. The jars can then be uncovered in a large cage, or if the flies are to be used in small branch type cages, they may be extracted by placing a double cone fly trap over the mouth of the jar. The flies migrate rapidly into the trap. this can be place in a refrigerator for a few moments, and the flies emptied into a smaller container. These containers can be carried to the field in a bucket of ice water, and the dormant flies placed in the small cages. It is possible to use ether technique, but we have found that this shortens the useful life of the insect.

17. On The Utilization of Jointless (j1) In Tomato Breeding

M. L. Tomes, K. W. Johnson, and E. C. Stevenson

Purdue University, Lafayette, Indiana

Since the shattering of fruit during pick-up by machine harvesters promises to be a problem, the possibility of using the jointless gene (j1) is still under consideration. Crosses between one of Dr. Munger's uujj lines and dwarf-vined, and between uujj and normal-vined breeding lines were made and a number of F2 progenies were grown in the 1962 field. In seeking desirable jointless recombinants, the location of this gene was brought home rather forcibly.

Five F2 progenies between dwarf lines and uujj yielded only four jj plants. These progenies had been selected for dwarfing in the seedling stage. Our first though was that j was linked to d+ and that we had eliminated most of the jj plants by discarding the normal-vined types. There were, in addition, seven F2 progenies of crosses between d+ lines and uujj. These yielded jj plants as follows: 3/98, 7/135, 4/118, 2/118, 6/104, 3/116, and 2 of 110. This is a total of only 27 jj plants in 799.

In every case the dwarf or normal-vined parent possessed resistance to Fusarium wilt. It is our practice to screen all breeding progenies for wilt resistance. Obviously, in the screening process most of the jointless plants were discarded. Both j1 and I (Fusarium immunity) are supposed to be in linkage group V. These data suggest a fairly close linkage. By subsequent progeny tests, three of the above 27 jj plants were found to be susceptible. They apparently escaped the original inoculation.

An aliquot of one of the above F2 progenies was grown elsewhere without inoculation and yielded 26 jj plants of 141. Both in this progeny, and above, some additional selection may have been practiced in the transplanting process, so no linkage calculations have been attempted.

18. Downy Mildew Resistant Broccoli Breeding Material Available From the New York State Agricultural Experiment Station, Geneva

John J. Natti and John D. Atkin

Downy mildew incited by Peronospora parasitica (Pers.) ex Fr. is one of the important diseases of broccoli, Brassica oleracea var. botrytis L. Resistance to the starin commonly found in New York was obtained from a selection from the broccoli introduction PI 189082. Under greenhouse test conditions, sporulation was sparse on the cotyledons, and only localized spots devoid sporulation developed on the true leaves of inoculated seedlings which originated from this selection. Under similar conditions, seedlings of the broccoli variety Waltham 29 were severely infected, and sporulation was heavy on both cotyledons and leaves. The resistance is conditioned by a single dominant gene.

Resistance has been transferred into Waltham 29 by backcrossing for six generations followed by two selfed generations plus one sib cross. Several lines have been developed which differ considerably, and probably none of the lines could be used in their present state as commercial varieties. Under field conditions, all lines show a high degree of resistance.

Seed of the homozygous resistant lines is very limited, but quantities are sufficient for distribution as breeding material to qualified plant breeders. This material will be released with two basic restrictions as follows: (1) if any variety should be developed from the material, the New York State Agricultural Experiment Station at Geneva is to be notified; and (2) seed of any varieties developed from this material is to be made available to New York processors.

The number of plant breeders desiring to receive seed is not known, and thus it is requested that those interested contact the authors before March 10. The available seed will be divided into lots sufficient to cover requests received by that date. A "memorandum of understanding" describing the material and explaining the conditions of release will be sent to those expressing interest. Seed will be mailed out upon receipt of the signed "memorandum of understanding" at the New York State Agricultural Experiment Station at Geneva.

Reference concerning testing techniques, etc.:

Natti, John J. 1958. Resistance of broccoli and other crucifers to downy mildew. Plant Disease Reporter 42(5): 656-662.

19. Letter to the Editor

The following note deserves your consideration. All of us appreciate the opportunity to exchange material. Let's express that appreciation by exerting the necessary effort to see that the originator receives an evaluation of the plant material he submits. Each of us desires this for the materials we send out. Let us be sure to extend the courtesy to those from whom we receive uncatalogued varieties or breeding lines.

"This variety testing does no good if a performance report, when requested, is not sent to the originator. Of the packets of seed distributed for trial last year, I have had, to this date, reports from 20% of the locations. I tried to facilitate reporting by sending a convenient mimeographed form in September or October.

Even if the line is a failure in other locations, the breeder wants to know. That, in fact, is the purpose of these tests. If the intent is to use a line as a parent, some evaluation is made during the season. If it is just an opinion, express it. Otherwise, this potentially valuable system of extensive testing will deteriorate."

L.C. Peirce

20. Uncatalogued Vegetable Varieties Available for Trial in 1963

This list is aimed at facilitating the exchange of information about potential new varieties, or new varieties which have not yet appeared in catalogues. Persons conducting vegetable variety trials who wish seed of items on this list should request samples from the sources indicated.

It is the responsibility of the person sending out seed to specify that it is for trial only, or any other restriction he may want to place on its use.

Crops are listed alphabetically, with lima beans and sweet corn listed under "L" and "S". For each entry the following information is given: designation, source of trial samples, outstanding characteristics, variety suggested for comparison (not given separately if mentioned in description), status of variety (preliminary trial, advanced trial, to be released, or released), and contributor of information if different from source of trial samples. Where several samples are listed consecutively from one source, the address is given only for the first.

21. Stocks Desired

AVAILABLE for plant breeders are stocks of pepper (Capsicum annuum) highly resistant to root rot caused by Phytophthora capsici, and tomatoes with moderate resistance to tobacco mosaic, derived from Solanum pennellii. Paul G. Smith, Vegetable Crops Dept., University of California, Davis, California.