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Hort. var. Rose {rosea) 30

Veronica latifolia (teucrium), Hungarian Speedwell

Hort. var. Rupestris 30

(Veronica Ion gifolia). See Veronica maritima
Veronica maritima {longifolia)

Hort. var. Blue Spire 30

Veronica maritima {longifolia) subsessilis, Clump Speedwell 38, 42

Veronica spicata, Spike Speedwell 22, 27

Veronica spicata alba, White Spike Speedwell 20, 27

Veronica spicata rosea, Pink Spike Speedwell 23, 27

(Veronica teucrium). See Veronica latifolia
Viola cornuta. Horned Violet

Hort. var. Fragrance 7, 27, 42

Viola odorata. Sweet Violet

Hort. var. Rosina 11

Violet, Horned. See Viola cornuta
Violet, Sweet. See Viola odorata

Wildindigo, Blue. See Baptisia australis
Winteraconite, Cilician. See Eranthis hyemalis cilicica

Yarrow, Fernleaf. See Achillea filipendulina

Yarrow, Pink Common. See Achillea millefolium roseum

Yarrow, Sneezewort. See Achillea ptarmica

Publication of this Document Approved by Commission on Administration and Finance

agricultural experiment station

Bulletin No. 393 June, 1942

Bay State,

A Red Forcing Tomato

Bred for Resistance to Leaf Mold

By E. F. Cuba

Leaf mold is a devastating disease of tomato in greenhouses and its control
is difficult and expensive. This bulletin describes a new greenhouse tomato
which combines resistance to certain strains of the fungus with desirable com-
mercial fruit type.



By E. F. Guba, Research Professor of Botany


Approximately 1400 tons of greenhouse tomatoes are produced annually in
Massachusetts for nearby wholesale markets. About 76 percent or 1070 tons,
known locally as the spring crop, are harvested during April to August, inclusive,
representing a value of $257,000. The remaining 24 percent or 336 tons, known
in contrast as the fall crop, are harvested from September to February ami
represent a value of approximately $101,400.' This production represents a value
or gross income to the greenhouse tomato growing industry of about $358,400
annually. It is estimated conservatively that production for the spring and fall
crops could be increased by 8 and 30 percent respectively were not the tomato
leaf mold disease, caused by the fungus Cladosporium Julvum Cke., a deterring
factor. This would represent an increase of about 85 tons or $20,400, and 100
tons or $30,100 for the spring and fall cropping seasons respectively, or approx-
imatelj' 185 tons and $50,500 annually. Losses in greenhouse tomato production
as the result of this disease occur in the same general proportion all over the world
where tomatoes are grown under glass.

Since 1925, the Massachusetts Agricultural Experiment Station has been en-
gaged in a study of the tomato leaf meld disease, and several bulletins and
scientific journal articles describing the results of these studies have been issued.
Since 1933, all of the effort has been directed toward the study of the reaction of
tomatoes to the fungus parasite, and the breeding of a commercially acceptable
resistant type. The serious nature of the disease and the inability of growers to
control it at reasonable expense and within the limits of usual greenhouse practice
have encouraged and justified this long effort.

As a result of this study, a new tomato resistant to certain physiologic forms
of this prevalent and devastating fungus has been developed. The tomato has
entered commercial production under glass and has proved acceptable to many
growers. Therefore, an account of the development and a description of the
tomato is now considered desirable.


The resistance of the Red Currant tomato to Cladosporium fulviim Cke.
was first recorded by Sengbusch and Loschakowa-Hasenbusch (10) in 1932 from
Germany and confirmed by Guba (6) in Massachusetts and Alexander (1) in
Ohio in 1934. This immunity leaction has been reported only for Lycopersicon
pimpinellifolium (Jusl.) Mill, and derivatives from it. Langford (9) in Ontario
found that, although no macroscopic symptoms ordinarily followed inoculation
of this species, the fungus penetrated the stomata and developed in the eaf tissue
to a very limited extent and in a few instances necrotic non-sporulating infection
flecks were produced from which the fungus was readily recovered. Bond (5)
in England found no external symptoms on the Red Currant tomato and
observed necrotic isolated cells only in immediate contact with the hyphae. On
inany other Solanaceae classed as immune, the course of infection after penetra-

■Compiled from statistics furnished by the Massachusetts Department of Agriculture, Boston.


tion by the fungus was essentially the same; and among other species in other
families an extensive mycelium was never developed after penetration, even
under favorable conditions. This historical background is offered to rail atten-
tion to the consistency of reports showing the high degree of resistance of the
Red Currant tomato to the Cladosporium fungus, and the definite lack of
sporulation even in those rare instances where the fungus was observed to cause
a yellowish area about the point of infection.

This new tomato was developed from cresses of Lycopersicon pimpinellifolium
(Jusl.) Mill, and L. esculentum Mill., two distinct species of tomato respectively
highly resistant and highly susceptible to tomato leaf mold. Three varieties of
esculentum tomatoes — Success, Belmont, and Break O'Day — were selected for
the first crosses after a comparative trial of varieties on outdoor trellis in 1933 at
Waltham. They are early maturing and bear large red tomatoes. Red color,
large fruit, and earliness were considered desirable, since the pimpinellifolium
tomato bears red fruits of extremely small size and because only red tomatoes are
wanted in the Boston market area.


The entire population of the first generation was alike for all plant characters
and for resistance to leaf mold. The population o" the second generation was re-
solved into various unlike, desirable and undesirable characters, and resistance
and susceptibility to the disease. Selections for desirable characters and for le-
sistance to the disease were continued for two further generations. There ap-
peared to be nothing significant offered by the progenies cf one hybrid not also
offered by those of the other two; but the fruit, being only ^ to 1 inch in di-
ameter, was wholly inadequate fcr size.

The varieties Success, Belmont, and Break O'Day under greenhouse culture
show many undesirable characters and, therefore, were considered unsuitable lor
further crossing with desirable types from the latest generations of the original
hybrids. For this purpose, and for a desirable greenhouse forcing type, an im-
proved selection of the Field Station Comet, now known as Waltham Forcing,
was employed. A large proportion of the greenhouse tomato production in the
Boston area is devoted to Waltham Forcing or s'milar types. Accordingly, this
type was judged to have the qualities most desirable for a greenhouse forcing
tomato. The objective then was to develop a type comparable to Waltham
Forcing and resistant to leaf mold.

Three successive backcrosses were made with Waltham Forcing, each after
selection for three or four generations from disease-resistant and desirable types,
and without regard for their original pedigrees. After the third backcrossing the
progenies were satisfactory for fruit size and yield, and seed of the second gen-
eration of the third backcross was distributed to a few growers for limited trial
and selection purposes for the 1939 spring cropping season.

In the fall of 1939, a larger F3 population was grown in several greenhouses.
The performance and the quality of the tomato were unusually promising, but
there were also some inherently bad features, notably an hereditary breakdown
manifested by yellowing, rusting, spotting, and necrosis of the foliage. Other-
wise, about 80 percent of the individuals in these plantings were highly resistant
to leaf mold and the foliage remained green and healthy throughout the entire
growth from the ground to the tops of the plants, or almost 7 feet. In contrast,
the remaining 20 percent of these plants and Waltham Forcing growing in the
same greenhouse were "burned up" by the disease. Several growers who met at
the greenhouses of Mr. Russell Eisenhaure, Concord, in the fall of 1939, to observe


this leaf mold resistant tomato were greatly impressed by its peiformance. This
demonstration furnished convincing evidence that there could be no mistake in
the choice of this tcmato where a crop failure or loss from leaf mold was feared
or existed. Therefore, it was decided not to wait until the tomato was perfected
before distributing more seed samples. This plan made available commercial
plantings from which further selections for resistance and desirable commercial
types could be made both by the writer and by the growers.

In the interval which has since elapsed, the tomato was made pure for
resistance to Cladosporium leaf mold, and was given the name Bay State (7).
The tomato has performed in a highly acceptable manner for many growers, and
approximately 25-30 percent of the greenhouse area producing tomatoes in the
fall cropping season of 1941 in eastern Massachusetts was planted to Bay State.

A loss of two-thirds of the yield of leaf mold susceptible varieties in the fall
cropp'ng season is not uncommon. A loss of 17 percent of the yield associated
with 45 percent of infected foliage has been recorded for the spring cropping season
(8). A comparison of the yields of resistant Bay State and susceptible Kondine,
both artificially inoculated with a spcre suspension of Cladosporium when 2 feet
tall, revealed an incieose of 54 percent in favor of Bay State. ^ One Bedford
(Massachusetts) grower who had been harvesting 10 to 12 tons of tomatoes of a
susceptible variety under devastating attacks of leaf mold in the fall cropping
season, reported increases of 2 tons and 6 tons for the fall cropping seasons of
1940 and 1941, respectively, with Bay State. A Concord grower, with a smaller
growing area, reported increases of IJ^ tons and 23^ tons for the fall cropping
seasons cf 1940 and 1941, respectively, as the result of substituting the Bay State

Without destructive occurrences of leaf mold, which is possible particularly in
the spring cropping season, Waltham Forcing is definitely superior to Bay State
in yield, and under such conditions no encouragement has been given to the
culture of the Bay State variety. Where destructive occurrences of the disease
have been experienced, or are feared, many growers have chosen and accepted
Bay State. The variety is still subject to improvement in the direction of a con-
sistently high yield and more uniformity in plant growth, but these are faults
which can be corrected by further selecting. Growers who are planting the Bay
State tomato are encouraged to make selections for further growing in their own
greenhouses from the most promising and desirable types. Such selections are
likely to show better adaptability to local conditions than those from outside
sources grown under different and variable conditions.


This tomato has been grown only in greenhouses to a single or double stem
trained to string or cane supports. The botanical characters ofTered here apply
to the variety under that system of culture only.

The Plant

Stem usually 4 feet long when first trusses mature. Growth period (from medi-
um sized plants that have not reached blossoming stage to first harvest in green-
house) 60-70 days. Habit rather rank, with both leaves and fruiting trusses
long and coarse.

^By correspondence, Plant Disease Division, Dept. Scientific and Industrial Research, Auck-
land, New Zealand, February 28, 1941.

Figure 1

Lower Surfaces of Tomato Leaflets, sfiowing diseased, dead areas overgrown with Cladosporium
mold. The entire foliage is ultimately destroyed.

Courtesy. Dr. G. T. Wchcr.

Figure 2

Inflorescence of the Red Currant Tomato, Lycopersicon pimpinellifolium ( Jusl.) Mill., showing
racemose and apical furcate habit and mature fruits averaging one half inch in diameter. X 1/6



Figure 4

F3 Progeny of Original Esculentum ~^' Pimpinellifolium Hybrid, showing segregation for siiscepli-
bility (left) and resistance (right). X 1 8

Figure 5

SiiscepSibilily and Kesislance to Cladosporium Leaf Mold.
Upper: Wallham Forcing (lefl), susceptible; Bay Slate (right), resistant.
Lower: Hay State X Clobelle (left), liiglily resistant; Michigan State (right)


Figure 6. Bay State Tomato.
Upper: Fruiting types in first commercial trial growing, fall cropping season mV)
'^''^^^ir^Tiyv^^AutZ rsT^^^'^' '"'-''"' '-'""-^ after^ars^eTecZ^for desir-

Figure 7
Bay State Tomato — fruiting performances under commercial growing conditions, November 1941

Figure 8

Bay Slate Tomato Fruits, sliowing stem and stylar ends (approximately lialf size), stem end cavity
(ttiree fourths size), and cross section stiowing interior structure.

^ m ""w ' 4i ^m^'-' W- ' W T " ' "'f " f

Figure 9. Bay State Tomato
Upper left: Common, oblong desirable type of fruit , u- ••

Upper right : A deeper, occasional type permissible for basket pack and not too seriously objection-
able for 5, fi, and 15 pound carton packs.
Center: Six pound carton pack.
Lower: Fifteen pound carton pack.



Leaves typically 4-6 inches apart along the stem; under good cultural condi-
tions 17-20 inches long X 15-22 inches wide; upper surface usually dark green,
lower surface pale green. Largest leaflets numbering 7-9, coarsely and deeply
lobed and irregularly dentate; bladelets 4-6 X 2-3 inches. Medium leaflets
9-13, typically 2 J^ X 234 inches long, slightly lobed, and coarsely and irregularly
dentate. Small leaflets usually 8-10, entire, slightly dentate, 134-1 H inches long
and wide, ovate. Smallest leaflets 7-10, ovate, 3^ inch long and wide. Petiolules
from 3/16 inch long for smallest leaflets to 3 inches for largest leaflets.

Flower Cluster

Flower cluster racemose, simple or furcate, usually with 6-14 or more^flowers;
the greater number associated with the furcate racemose habit; developing and
maturing usually 4-7 fruits per cluster. Corclla lobes usually 6, and generally
3,'g inch long; calyx lobes or sepals usually 6 or 7, narrow, linear, usually 5/16
inch long. Connivent anthers usually ^g inch long, concealing the whole pistil.

Peduncles often 12 inches long, racemose, simple or branched, spreading; dec-
linate, or vertical with the axis or stem in the late fruiting stage from an excessive
weight of fruit, and sometimes constricted near the stem therefrom; pedicels
1-1 J^ inches long, rarely up to 2 inches.

Fruit Exterior


Rather long, 1-13^ inches; 1^-3/16 inch wide at base, acuminate, frequently 6
or 7, rarely 8, equal and distinct, or 5 distinct and 1 furcate, or 6 distinct with 1
broader than the other 5; straight or slightly curved, erect or divergent, and en-
veloping the coarse, short pedicel which is about 3^ inch long. Sepals and pedicel
light bice green^ or of slightly darker or lighter shades.

Immature Fruit

Uniformly apple green, mineral green, callisle green, sometimes slightl}- darker
about the stem end.

Mature Fruits

Medium size, firm, weighing 13^-6 ounces, typically 33^-5 ounces each (first
grade) and running a high percentage to first grade; oblate or oblong in polar
section, round in transverse section, sometimes flattened or oblong when viewed
from the side, measuring typically 1\^-1Y^ inches transverse diameter, and IJ^-
ly^ inches polar diameter, the typical form established before fruit is half grown.
Cavity Y^T^i i"ch deep, broad, sloping gradually; side of cavity slightly lobed
with 3 or 4, rarely 5, somf times prominent creases radiating from the corky ring.

Corky scar tissue (stem abscission layer) circular, shallow, concave; cork^'
ring not prominent, usually 3,-^-7/16 inch in diameter, stem adhering rather firm-
ly. Stylar end flattened, smooth, usually a slight depression or shallow basin
piesent about stylar scar in ripened fruit. Stylar scar small, 1/16-1/8 inch in
diameter, 3 o. 4 pointed, not too conspicuous or objectionable, often a mere dot.
Streaks radiating from the points of stylar scar but relatively inconspicuous in
mature fruit (dark green streaks boidered by pale green in green immature fruit).
Flavor mildly subacid

Comparative susceptibility to circumferential and radial cracking not known
or observed. Fruit stems snapping off easily at the first node. Color scarlet to

'Color Standards and Color Nomenclature; Ridgway.


scarlet red, uniform at maturity but progressing toward the stem end; during the
ripening process yellow green or chrysolite green about the stem end and ochraceous
orange or ochraceous buff below, changing to flame scarlet, and finally to a uniform
brilliant scarlet. Skin yellow.

Fruit Interior

Outer and inner walls medium thick, typically 34 inch in thickness and uniform,
light coral red or peach red to scarlet red. Coloring cf inner walls retarded. Cells
3 or usually 4, regular in shape and arranged as segments of a circle. Central
mass well-defined and firm; the core medium, palei , slightly green or retarded
in coloring.

Lobes of placentae opposite each other and usually 4, 1 to each cell; cells
large, moderately filled with pulp and seed. Seeds medium in numbers per
fruit and per un"t weight of fruit.


In Massachusetts resistant to certain forms of tomato leaf mold caused by the
fungus Cladosporium fulvum Cke. For commeicinl market use and considered
to be a good shipper and keeper.


In the fall of 1940 a serious attack of leaf mold occurred on the Bay State to-
mato in a Swansea (Massachusetts) greenhouse. Previously in this place and
elsewhere Bay State had been highly resistant.

Earlier in 1940, Alexander-'(3) reported Bay State, Vetomold, Glcbelle, and
Red Currant susceptible to another physiologic form of leaf mold. Vetomold
is a red fruiting, leaf mold resistant type originated by Langford (9), and Globelle
a pink fruiting resistant type originated by Alexander (1, 2). Both were derived
from Z. pimpinellifolium (Jusl.) Mill, which originally was found tc be highly
resistant or for all practical purposes immune to the Cladosporium fungus.

Material of the leaf mold from Swansea was used for artificial infection pur-
poses at Waltham. Bay State, Vetomold, Globelle, and Red Currant, which
had always been highly resistant in previous performances, were in this test
susceptible. On Red Currant, necrotic foliage infection areas were numerous
and were covered on the lower surface with a considerable growth of leal meld.
Heretofore, such a phenomenon en Red Currant had not been observed. The
progress of the disease was, however, much less serious on Red Currant than on
Bay State, Vetomold, and Globelle. The new form of Cladosporium has appeared
in other locations in Massachusetts. It is less virulent and destructive on Bay
State than the prevalent, normal form of leaf mold on Waltham Forcing and
other locally grown varieties.

The disease caused by this new form advances slowly from points of infection,
giving rise to yellowish infection flecks between which the normal green color is
retained for a time, producing the eflfect of a checkerboard. Molding and spcr-
ulation on the lower surfaces of the leaves is less abundant, or is delayed at least
for some time where desirable watering, heating, and ventilating practices are
followed. Where excessively damp conditions are encouraged or disregarded,
the tomato plants ultimately become seriously affected. The fact that the new
form of leaf mold is not now generally prevalent, and seems less virulent than the
original form, would appear to render the status of these derivatives of "pimpi-
nellifolium" X "escule.'itum" crosses encouraging.

'Correspondence, February 16, 1940.


It is interesting to note here that Langford (9) originally repotted four distinct
physiologic forms of leaf mold to which Vetomold is resistant. Bay State and
Globelle share the same measure of resistance to these forms, since each derived
its resistance to the fungus from Red Currant which in widely scattered centers
throughout the world has shown a high degree of immunity. The new form to
which Vetomold and other derivatives of Red Currant are susceptible is regarded
by Bailey and Langford (4) as a fi^th physiologic form.


Alexander (1) recognized five arbitrary classes of resistance: excellent and good
grouped together as resistant; and fair, poor, and none grouped together as sus-
ceptible. These pathological reactions to infection on various species and va-
rieties of tomatoes were used by Langford in the classification of five strains of the
fungus. Cultural studies also have revealed numerous strains of the fungus which
produce different pathological reactions.

A completely susceptible type of infection is characterized by a progressive
browning and necrosis of the foliage and profuse molding and sporulation when
humidity is relatively high. Infected foliage Is destroyed progressively and
comparatively early. Under relatively dry conditions, the progress of infection
is characterized by slowly expanding brown necrotic spots with only a limited
amount or no sporulation on the lower surface. Reactions within this range are
found on Ailsa Craig, Potentate, VValtham Forcing, Kondine, Comet, Michigan

In contrast, a partial resistance or less virulent type of infection is manifested
on other varieties. Infections are restricted to a smaller area and they are con-
spicuously yellow on the upper surface. Both necrosis and sporulation occur
eventually but to a comparatively slight degree, and they are restricted to the
center of the spots. The surrounding yellow areas are more conspicuous above
than below. In a continued moist atmosphere the final reaction may be com-
parable to complete susceptibility, but under conditions of relatively low humidity
there is little or no sporulation. This type of infection is shown by Norduke,
Maincrop, Up-to-Date, Stirling Castle, Bay State, Vetomold, Globelle.

A similar reaction expressing a still greater degree of resistance or extreme re-
sistance is manifested by progressively enlarging 3'ellowish infection areas. The
centers ultimately become necrotic and sporulation occurs in and from the centers
only in a moist atmosphere. This resistance is manifested by Lycopersicon hir-
sutiini Humb. and Bonpl. and L. pimpinellifolmm (Jusl.) Mill.

Immunity or complete resistance to the fungus is offered by L. peruvianum (L.)
Mill. The macroscopic symptoms of infection are of an expanding yellowish
type, indefinitely outlined, extremely rare, and non-sporulating. This type of
reaction was originally exemplified by Red Currant, L. pimpinellifolium (Jusl.)
Mill., to all of the known forms of Cladosporium fulvum Cke. Attempts to hybrid-
ize L. peruvianum and L. esculentum have failed completely. Pollination of
"esculentum" flowers with pollen from L. peruvianum gives rise to tomato fruits
of good size but no seed is ever produced.

Langford (9) described a kind of partial resistance manifested by progressively
enlarging, necrotic, non-sporulating infection areas developing under high atmos-
pheric moisture conditions and resembling symptoms following inoculation with
the commc>n virulent strain of the fungus on susceptible varieties under con-
ditions of relatively low humidity.

Confirmation of the identity of the several reported strains of Cladosporium
fulvum Cke. is desirable. In view of the difficulty and uncertainty ol providing
and maintaining at Waltham pure culture atmospheres for infection purposes,


a study of strains or physiologic forms of the fungus was not undertaken. It is
evident, however, that in addition to pathological reactions manifested by
Lycopersicon, cutaneous responses of persons allergic to the fungus should also
be extremely useful in differentiating physiologic forms.

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