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Vegetable Improvement Newsletter No. 12, February 1970
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Compiled by H.M. Munger, Cornell University, Ithaca, New York

1. Presence of Third Strain of Lima Bean Downy Mildew

R.E. Wester

U.S. Department of Agriculture, Beltsville, Md.

A third strain (strain "C") of downy mildew of lima beans (Phytophthora phaseoli, Thaxt.) was discovered in the fall of 1969 on G 1 bush lima beans at Elmer, New Jersey. This was the area where the "B" strain was discovered about 10 years ago and where the "A" strain has always occurred. This could be the area where downy mildew first originated. When G 1 and G 2 baby lima bean lines were grown in many other areas in New Jersey, Maryland, and Delaware where Thaxter became infected with downy mildew strain B of the fungus, was developed to replace Thaxter. Since Thaxter had a life-span of about 10 years before strain B became widely spread, G 1, which will be released early in 1970, should also have a life expectancy of about 10 years.

2. Newer Baby Limas

R.E. Wester

U.S. Department of Agriculture, Beltsville, Md.

Five new green-seeded lima bean lines [ 568 BG (NJ 698), 668 BG (NJ 699), 868 BG (NJ 6910), 968 BG (NJ 6911), and 1168 BG (NJ 6912)] were increased in 1969 by Joseph Steinke of the South Jersey Experiment Station, Bridgeton, and tested at Georgetown, Delaware; Bridgeton, New Jersey; and Beltsville, Maryland. These lines, resistant to downy mildew strains A and B, are earlier, shorter, and with greener seed coats and cotyledons than Thaxter, Early Thorogreen, G 1, and G 2. Since the beans mature at one time, these lines are well adapted for mechanical harvesting. All are vigorous germinators.

3. Newer Fordhook Lines

R.E. Wester

U.S. Department of Agriculture, Beltsville, Md.

Three new green seeded Fordhook lines, U.S. 169G, U.S. 269G, and 369G, resistant to downy mildew strains A and B were increased by Joe Steinke of South Jersey Experiment Station in 1969. They were also tested at Seabrook, N.J. and Beltsville, Maryland. These are earlier than Green Fordhook 861, are stronger germinators and have greener seed coats and cotyledons. Since the pods mature at one time, these lines are well adapted to mechanical harvesting.

4. Dover Bush - New Lima Bean Variety

R.E. Wester

U.S. Department of Agriculture, Beltsville, Md.

DOVER BUSH baby lima bean was formally released to the seed trade by the U.S. Department of Agriculture in January 1970. This variety is resistant to downy mildew strains A and B. The parents of Dover Bush are Thaxter and Piloy. Piloy (P.I. 189403) contributed resistance to downy mildew strains A and B. Thaxter contributed resistance to the A strain, green cotyledons, and light green seed coats.

Dover Bush was developed primarily to replace Thaxter which is susceptible to the B strain of the downy mildew fungus now widespread in the Middle Atlantic Coast area.

In the Middle Atlantic Coastal area Dover Bush is 5 to 10 days later than Thaxter, 20 to 30 percent larger with a more extensive root system, and when planted at a lower seeding rate of 20 to 30 percent than Thaxter with weeds being controlled, this variety outyields Thaxter by 20 to 30 percent.

Under California conditions in 1969 Dover Bush showed considerable more drought resistance as well as heat resistance than Early Thorogreen and Thaxter.

The pods and beans of Dover Bush are similar to Thaxter. The variety has been released to seed companies for stock seed increase.

5. Progress in Sweet and Supersweet Corn Breeding for the Tropics

James L. Brewbaker

Dept. of Horticulture, University of Hawaii 96822

The development in Hawaii of fresh corn germplasm adapted to the tropics centers on the production of single cross hybrids and of synthetic varieties. Conditions in Hawaii have permitted rapid genetic advance in selection of stripe- ("mosaic") and blight-resistant lines with high earworm resistance. Current tests annually involve about 300 sweet corn hybrids and 50 shrunken-2 hybrids, together with about 25 varieties, composites or synthetics.

Hawaiian Hybrid H68, released in 1968, has shown wide general adaptability and success throughout the warm tropics, and has proved to be a superior hybrid in many of these tests. Its limiting factors in certain areas include its blight, smut, downy mildew, and rust susceptibility. H68 is in small-scale commercial production in several countries. New releases are planned in 1970 to supplement previous releases H38 (bantam type) and H68.

A complete list of composites and synthetics available in Hawaii can be obtained from the author. These include four shrunken-2 composites, 3 amylose-extender-waxy composites, and 2 brittle-1 composites. Among these, the brittle-1 stocks appear most promising in seed viability, while all have been reasonably comparable in their quality and post-harvest retention of sweetness (due to high sucrose levels). Most of these composites have a vigorous Hawaiian Sugar background.

Additional stocks include floury-2 and opaque-2 converted sugary-1 composites, as well as floury-2 converted inbreds of Hawaiian Sugar origin. Also available are a Tms tropical sweet composite, and some Ht composites (blight-resistant gene, Ht1). Among a dozen sugary-1 stocks in our program are 3 sources of Hawaiian Sugar, 2 synthetics of evident superiority in quality and yield to the variety, 4 composites with blight resistance from different sources, and one composite segregating for downy mildew resistance.

Plantings are made essentially every month of the year in Hawaii, some in cooperation with contracting seedsmen on the island of Molokai. Composites are thus advanced at least two, and generally three generations each year. Excellent results have been obtained in selecting for tenderness by harvesting at fresh corn stage (about 70 days), bite-testing, and drying selected ears for replanting. Recovery of satisfactory tenderness (tropical standards) has been achieved in two generations (selfing) from crosses with tropical flint stocks like Guatemalan and Narino.

6. Excellent Source for Better Roots on Sweet Corn

Dr. Stuart N. Smith, Consultant

Sweet Corn Genetic Service, 808 E. Lincoln Way, Rte. #2, Ames, Iowa 50010

Sweet corn has usually been more susceptible to root lodging than field corn. This may be partly because the plants and root systems are often smaller and partly because of intensive work done by field corn people to overcome the problem. A massive root system which resists lodging also helps to increase drought resistance. With modern methods of harvesting sweet corn, however, it is increasingly more important to improve wind resistance after the commercial crop. Inbreds which have high wind resistance after the tasseling stage usually have a substantial surface root growth from the first node or two above the ground as well as deep root penetration.

The best source I have found for massive root development of this type is the inbred N28, from the Nebraska Experiment Station. In crosses with sweet corn it contributes well filled ear tips, good tight husk protection, a tendency toward two ears and, of course, exceptional roots. On the negative side, it tends to produce tapering ears and a pericarp tougher than most sweet corn. As a root source, however, it may have some value in sweet corn with adequate backcrossing and selection to recover texture and tenderness.

7. Aids for the Plant Breeder

W.R. Sitterly

Clemson University Truck Experiment Station, Charleston, S.C.

Cucumbers: Difolatan, manufactured by Chevron Chemical Company, has been cleared for use to control soil-borne cucumber fruit rotting organisms. It should be applied in the field at last cultivation and before vining begins.

Difolatan may be used at 2 lbs. of active ingredient in as little as 25-30 gal. of water per acre. Cover the entire soil area. Difolatan may also be used in the greenhouse as a soil fungicide drench after planting, and as a bath solution in which to submerge clay pots before they are filled with soil and planted.

Benlate, manufactured by DuPont Chemical Company, is a systemic fungicide which has not been cleared for commercial use. Plant breeders, however, should find it a valuable tool for controlling cucurbit powdery mildew, anthracnose, and gummy stem blight. Benlate may be applied at 4 ounces of active ingredient in as little as 25-30 gal. of water per acre, and is far more effective with the addition of a spreader or spreader-sticker. Two week intervals between applications are routine, and at the Clemson Truck Station this interval has been extended to three weeks. Generally Benlate is ineffective against the obligate parasites such as downy mildew.

In the greenhouse, Benlate is particularly effective in controlling powdery mildew on plants maturing fruit for seed or in just keeping any other cucurbit experiment clean of powdery mildew.

8. Genetic Male Sterility in Onion

A. Andrasfalvy

Research Institute of Horticulture, Budapest, Hungary

During the search for cytoplasmic male sterility in Zittauer onion maintained at the Research Institute of Horticulture, Budapest by K. Csatari-Szuts, several male sterile individuals were saved in 1959. This sterility proved to be stable in subsequent years either in sister bulbs or in F2- segregants derived from male fertile outcrosses of the original male steriles. More than 150 test-crosses made during a seven year period with different pollinators including several varieties, yielded practically no male steriles, whereas F2 and backcross generations gave the expected Mendelian ratios. First in 1967 uniformly male sterile families appeared in combinations of another male sterile plant selected from a variety named "Valensiya" of a Russian sample. Further tests made in 1968 and 1969 with male steriles received from Dr. W.H. Gabelman proved that the male sterility found in Zittauer is of genic nature, and the later found type is identical with the cytoplasmic one used all over the world in hybrid seed production. Testcrosses of Zittauer pollinators derived from the original population revealed a N ms ms genotype.

As a symbol it would be better to propose ms for the genic male sterility, however, it is reserved for the traditional nuclear gene interacting with cytoplasm S (this gene should be rather named by the Rf+ symbol), so it remains to choose the ms-2.

The genic male sterility may be useful in a double cross program e.g. as the mother line of the pollinator F1 parent especially if some linkage could be found with a vegetable marker like glossy or different scale color.

9. Inheritance of Mottled Leaf in Cucurbita Moschata

Dermot P. Coyne

University of Nebraska, Lincoln, Nebraska

Previous workers have reported that the mottled leaf character in Cucurbita pepo and C. moschata was controlled by a single dominant gene. Using C. moschata, I studied the segregation for the mottled leaf trait in the F2 generation derived from the reciprocal crosses of the varieties New Hampshire Butternut x Hercules. Hercules has mottled foliage while N.H. Butternut has normal green foliage. There was considerable variation among plants for the mottled leaf trait, ranging from severely mottled to very slightly mottled. Previously workers in studying other species did not mention and variation in the degree of mottling in the segregating generations. In the F2 reported here, all plant possessing any degree of mottling were counted in one group. A satisfactory fit to a 3:1 ratio of plants with mottled or normal leaves indicated that this trait was primarily controlled by a single dominant gene but the variation in the F2 indicated that modifying genes were also involved. This trait may be a useful genetic marker.

10. Regulation of Flowering in Squash by Ethrel and Possible Usefulness in Hybridization

Dermot P. Coyne

University of Nebraska, Lincoln, Nebraska

Many workers have shown that Ethrel treatment influenced the sex expression of cucumbers. An experiment was conducted by the author to determine the effect of Ethrel sprays on the expression of sex in Cucurbita moschata cv New Hampshire Butternut. The following concentrations of Ethrel were used, 50, 100, 250, and 500 ppm. The sprays were applied when the first true leaf was about one inch in diameter. Ethrel, 250 ppm, applied nine times at weekly intervals caused the plants to produce only female flowers. None of the other spray applications changed significantly the female/male flower ratio. The number of fruit was significantly increased under the repeated Ethrel spray treatment but there was no significant difference in total yield between any of the spray treatments and the control. Under the repeated spray treatments the mean size of the fruit was reduced.

It was of interest to me to conduct this experiment because it had been reported (HortScience 3: 272, 1968) that the F1 between N.H. Butternut as female with crookneck butternut, produced only regular butternut shape. I have found a small number of crooknecks in the F1 between N.H. Butternut and the other crookneck types. Crookneck is a serious rogue in Butternut squash and many stocks have a high frequency of this type. I have also found that in crosses between the small fruited N.H. Butternut x large fruited Butternut that the F1 showed dominance for large fruit size. I observed in 1969, no heterosis for yield or components of yield in crosses between a small number of Butternut cultivars. N.H. Butternut was one of the cultivars used in these crosses. It is suggested that the frequency of crooknecks in true large fruited butternut types could be considerably reduced by developing F1's between particular present large fruited types (unstable for fruit shape) with the N.H. Butternut as female. Treatment of plants with Ethrel could be used to develop all female plants for use in crossing with selected pollinators.

11. Response of Cucurbits to Ethrel

R.W. Robinson, Thomas W. Whitaker and G.W. Bohn

Cornell University, Geneva, New York, and Crops Research Division, ARS, LaJolla, California

A device or technique that has the possibility of altering the timing of sex expression, and can be manipulated by the plant breeder would have many advantages for experimental work with cucurbitaceous crops. Ethrel (2-chloro-ethylphosphonic acid), a growth regulator, inhibits the production of staminate flowers. This capability if exploited properly should make the production of hybrid seed of cucurbits less costly. Also, where species crosses are desired, synchronization of the flowering period of different species can be controlled by the breeder. These are two of the useful possibilities presented by this chemical; others will no doubt be found.

Studies at Geneva, New York, have demonstrated that hybrid seed of monoecious cucumbers can be produced at low cost with the aid of Ethrel. The female parent produces only pistillate flowers for an extended period after treatment with this growth regulator, and all open-pollinated seed produced during this period is hybrid. This method of hybrid seed production would be even more advantageous for other cucurbits, which lack a genetic system for gynoecious sex expression.

We have had promising results with squash. Studies at LaJolla, California, of cultivars of Cucurbita pepo L., C. maxima Duch., C. moschata Poir., and C mixta Pang. responded to 250 ppm applied in the first true leaf stage by producing only pistillate flowers at the first ten nodes. Genetic differences in response were noted, with the most persistent effect occurring with bush cultivars of C. pepo. A similar treatment applied to andromonoecious cultivars of Cucumis melo L. inhibited staminate flower production but did not induce formation of pistillate flowers, although perfect flowers were produced earlier than normal.

12. Experience with Excessive Activity in the Cotyledonary Axils

T.O. Graham

Horticultural Science Dept., University of Guelph, Guelph, Ontario

From 1949 to 1955 Professor V. Chanasyk was in charge of tomato selection work at the Research Station, Beaverlodge in the Sub-Arctic selection of Alberta. In 1963 he gave seed of the selection Beaverlodge 48-17-1221 to the University of Guelph. The parentage was as follows: (FARTHEST NORTH x FARGO YELLOW PEAR) x FIRESTEEL x L3700. The L3700 is a Research Station number from Ottawa, Ontario. It was selected from a cross made at Ottawa, namely, FARTHEST NORTH x POLAR CIRCLE. It underwent further selection at the C.D.A. Research Station at Lethbridge, Alberta and when sent to Beaverlodge from Lethbridge it carried the number L3700# 2.

In 1963 it was noted that many plants of this Beaverlodge stock were branching in the axils of both cotyledons. It was decided to see if this characteristic could be fixed. As a result seed from plants displaying excess activity in the cotyledonary axils was sown in the greenhouse in the winter of 1967-68. Out of 50 plants 23 had branches growing out of the axils of both cotyledons. In every case except one these plants had four leaves above the cotyledons before the first naked fruiting truss was reached on the mainstem.

In 1968 seed was sown at Guelph from the plants which had cotyledonary branching in 1967-68. In transplanting the resulting plants to the open field, cotyledonary activity was partially destroyed. Where maximum success is to be obtained indoors one must sow the seed in pots and thin out the seedlings to one plant per plot. It is necessary outside to sow directly without transplanting. In both these cases the cotyledons will not be damaged. Even where cotyledonary activity is disturbed by transplanting the plants are more uniform than those that trace back to the same seed source but have not been selected for cotyledonary activity.

In the winter of 1968-69 a total of 55 plants were grown indoors from seed harvested in 1968. Out of these, 25 plants had strong branching in the axils of both cotyledons. These had their first ripe fruit on an average of April 18. The remaining 30 did not display cotyledonary activity and the average for their first ripe fruit was April 24. Out of the 25 plants there were 18 with only 2 naked clusters per plant on the main stem. This makes it evident that in Beaverlodge types one is dealing with an entirely new type of plant and one in which the lower growth is so active that apical dominance is inhibited and top growth is curtailed. This allows the plant to ripen an abundance of fruit on the lower branches near the ground level.

There is evidence that when the concentration of fruit is close to the ground level earlier ripening will commence. Also, concentrated ripening becomes rapid. In 1969, out of 217 transplants of Sub-Arctic Delight, there was an average of only 25.5 days per plant before the yield became 100% ripe.

The seed harvested in 1968-69 from the 25 plants expressing activity in the cotyledonary axils was sown in the greenhouse on June 16, 1969. It was sown in 353 pots and was eventually thinned down to 353 plants. Of these, 113 plants were on the north side of the greenhouse. A total of 23 plants present in this population expressed no activity in the cotyledonary axils. This means that the inheritance is subject to environmental control and that there is more than one gene controlling the phenotype.

Several workers have shown that a count of the number of branches as one goes from branch to branch up the main stem of the plant will differ with differences in temperature. There is a strong indication that the number of branches present is under polygenic control. Part of the difference between plants down the row in Ontario must be caused by this polygenic response. It is likely then that the expression of excessive branching in the cotyledonary axils is also polygenic and is moving in concert. While activity in the cotyledonary region may not contribute greatly to the stability of response it certainly makes a valuable marker for extreme earliness, and rapid overall ripening. It also helps in the overcoming of apical dominance and contributes towards smaller plants and increased population density. It will contribute in Ontario towards obtaining plants which are early enough for once-over harvesting. In fact, the only hope that exists right now in short season areas for an outdoor sown, machine-picking type is the fact that work at the Sub-Arctic Stations, both at Beaverlodge and Fort Vermilion, is of necessity driving the tomato plant closer and closer to ground level.

Seed harvested from the previously mentioned 240 plants formed the basis in 1969 of the new salad tomato namely, Sub-Arctic Delight. Seed was also gathered from 300 plants which were sown in April 29 and transplanted outdoors on June 6. The average date of first ripening for all 300 plants was August 3 as contrasted to Fireball on August 20.

From the standpoint of indoor pot culture, when seed was sown in 1969 on May 21 and transplanted on June 11 the first crop under glass was harvested on August 12. The crop was completely ripe in three weeks and the plants discarded on September 7. It is possible to have 3 indoor crops a year.

13. Expression of Transference of Branching in the Cotyledonary Axils When Transferred to a Normal Plant Type

T.O. Graham

Horticultural Science Dept., University of Guelph, Guelph, Ontario

A cross was made at the University of Guelph between Guelph #81 and CHANASYK EARLY from the University of California which traces to 48-2111-A from the Research Station at Beaverlodge, Alberta. This last mentioned variety when grown at Guelph carries a percentage of plants present in any population which have branching in the cotyledonary axils. The #81 in the cross traces back to six parents which are Pink Tanggula, High Crimson, Earliest of All, Early Bird, Campbell #128, and Filipino #2.

In the F2 from this cross out of 5 plants, 3 had branches in the cotyledonary axils. These were crossed with the Kanatto variety. In the resulting F2 one plant out of five had branches in the cotyledonary axils. Seed was saved from this plant and in the next or F3 generation, consisting of 10 plants, all had cotyledonary activity in the axillary area. Seed was saved from these in 1969 to make up the variety Crimson Sprinter. In this case, as well as many others, the transference of excessive activity in the cotyledonary axils has proved easy to accomplish.

It was found that plants of Crimson Sprinter have long branches in the cotyledonary axils at times up to 4 1/2 feet. These, under conditions at Guelph, have a nutritional advantage which causes the naked flowering clusters on the upper part of the plant to abort.

Although the plants are not self-pruning in type the aborted clusters give the plant a similar effect. It is an entirely new type on plant in that it terminates its own growth like self-pruning types but still has the normal three leaves between the naked fruiting trusses on the main stem. For this reason it carried good leaf protection. Those working with mulches will be interested in how well the long axillary branches, barely above ground level, anchor the mulch. The fact also that the nutrient advantage held by the lower branches is such that it aborts the flowers on the top growth will not escape the attention of those advocating plant pruning by either chemical or mechanical means.

14. Possible Correlation Between Earliness and the Proximity of the Plant to Ground Level

T.O. Graham

Horticultural Science Dept., University of Guelph, Guelph, Ontario

Sixteen stocks tracing to the Research Station at Beaverlodge, Alberta, were tested for earliness. For a check the varieties ROCKET, FIREBALL and COLD SET were used. It has been found at Guelph that extreme earliness is often associated with the proximity of the plant to ground level. This is denoted by the number of leaves present as one goes up the plant from ground level until the first naked fruiting truss on the main stem is reached. Examples follow:

Average Number of Leaves from the base of plant until first fruiting truss is reached
Number of different varieties and stocks
Number of Plants
Average Date of First Ripe Fruit
July 28.1
July 30.0
Aug. 8.5
Aug. 3.4
Aug. 1.0
Aug. 2.0
Aug. 13.8
Aug. 10.8
Aug. 9.2
6.0 (Rocket)
Aug. 5.8
7.0 (Cold Set)
Aug. 18.6
7.2 (Fireball)
Aug. 19.8

15. TMV-Resistance Breeding in Tomatoes

G. Meszoly

Agricultural Experimental Institute of Duna-Tisza Koz, P.O. Box 116, Kecskemet, Hungary

The most effective control of TMV infection is the breeding of resistant varieties.

In Hungary complex species hybrids were developed by crossing wild species and cultivated varieties. A reliable inoculation method in the greenhouse was worked out (with local virus strain mixtures applied three times during the vegetative period). The progeny examination of the selected plants was done in the field the following year. Selection must begin at F2 paying attention to interrelations between environment and resistance. More than 2 backcrosses must not be done. TMV-resistance may be linked with certain fungi-resistance; the TMV and Cladosporium resistance of the species hybrids in Kecskemet were developed simultaneously. In our comparison trials of 1967 and 1968 our earlier and newly developed varieties and strains and some resistant breeding lines from abroad were tested.

Reliable resistance was found in: Kecskemeti Fajhibrid 1740; K. Fh. 1589; K. Fh. 1763; K. Fh. 1738; K. Fh. 1119/1; K. Fh. 1120/1; strain Alexander; W-21366. The economic value of our best species hybrids is as good as that of the commercial varieties. What we want now is to introduce more genes of resistance into the varieties.

Summary of Variety Releases
Dr. Gy. Meszoly

Varieties released in 1967:
K 42 x K torpe F1 = semi-determinate, green shoulder, early table and processing variety
K Det. San Marsano = semi-determinate, uniform ripening, for processing
K merevszaru = determinate, green shoulder, early table
K konzerv = semi-determinate, green shoulder, processing variety
Varieties which will be released in 1969:
Kecskemeti 507 = semi-determinate, uniform ripening, early table
Kecskemeti-3 F1 = semi-determinate, uniform ripening, early table
K. export = semi-determinate, uniform ripening, early table


  1. "Nemesitett novenyfajtakkal vegzett orsagos fajtakiserletek eredmenyei". Orszagos Mezogazdasagi Fajta- es Termelestechnikai Minosito Intezet Kiadvanyai. 1959-1968.

16. Uncatalogued Vegetable Varieties Available for Trial in 1970

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. 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.

17. Stocks Desired