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Bulletin - Massachusetts Agricultural Experiment Station (Volume no.379-398) online

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oxide with cucumber, cress, beet, tomato, and chicory. Only with pea did Sper-
gon give better results than potassium dichromate. With tobacco, red copper
oxide as a seed treatment gave the best results, Spergon the poorest; but none
of the seed treatments gave as good results as did formaldehyde treatment of soil.

Sodium nitrite, 1.5 to 3.0 gm. per square foot, applied to soil immediately after
seeding, was injurious to crucifers and to pea, not to cucumber, beet, and chard,
and it markedly increased the number of plants which lived. Lacking anything
better, it could be used as a soil fungicide with some plants, but it did not give
so good results as did much lighter applications of potassium dichromate.

Chromates and dichromates of potassium, ammonium, and sodium, applied
in solution to soil immediately after seeding, were found to be highly effective soil
fungicides, as effective as formaldehyde even in light applications. And, if prop-
erly used, they were quite safe as regards effects on germination and growth of
seedlings, except with cabbage and other crucifers. Potassium dichromate, 0.4
or 0.45 gm. per square foot (about 43 pounds per acre), was usually enough for
protection and great improvement in the stands of seedlings whether the pH value
of the soil was 5.6 or 7.1; but the treatment was safer and less likely to retard



20 MASS. EXPERIMENT STATION BULLETIN 398

growth in the acid than in the slightly alkaline soil. Dichromates usually gave
somewhat more complete protection and, if used in unnecessarily heavy applica-
tions, retarded growth of seedlings more than did the chromates. But if applied
at the time of seeding and at the rate of not more than 0.45. gm. per square foot,
the chromates and dichromates of potassium, sodium, and ammonium were
without ill effect on cucumber, beet, chard, pea, and bean; and the chromates of
potassium and ammonium, especially the latter, gave very good results. Potas-
sium dichromate was most effective and safe when applied to soil immediately
after seeding. Applied 24 hours later, it retarded germination of seeds of some
species. It gave satisfactory control when applied to soil two weeks before seed-
ing but was less effective when applied more than three weeks before seeding.
Chromate and dichromate of potassium, as used, gave more complete protection
than did the corresponding salts of sodium. Chromic acid gave superior results
only with beet; and the chloride, nitrate, and sulfate of chromium were almost
completely ineffective.

Cresol, in as light an application as L5 cc. per square foot, immediately after
seeding, gave good control, almost as good as did formaldehyde.

A very light application of formaldehyde (4.9 cc. or one teaspoonful per gallon
of water) was most effective when applied to soil immediately after seeding, de-
cidedly less effective when applied more than 24 hours after seeding. Growth of
beet, cucumber, and lettuce was improved by applications made not more than
8 hours after seeding, but seedlings of pea were injured when the first application
was made 24 hours after seeding.

When nutrients in the form of potassium nitrate and precipitated bone or
Ammo-Phos were added to a solution of formaldehyde and applied to soil at the
time of seeding, the fungicidal action of the formaldehyde was unimpaired. But
in a good sandy loam, the growth of seedlings of pepper, eggplant, beet, and cu-
cumber was improved as much by formaldehj'de alone as by formaldehyde plus
the nutrients.

Starter solutions applied to the soil around tomato plants as they are set in the
field cannot, w'thout danger of chemical injury to the plants, carry enough for-
maldehyde to be effective against soil fungi.

Lacking chemicals, seeds of some kinds, not all, may well be sown on a layer of
sphagnum, overlying soil. Damping-off was well controlled in this way, although
not so completely as by formaldehyde treatment of soil. Sphagnum so used gave
good results with lettuce, cabbage, and cress, the two latter being especially
susceptible to injury by formaldehyde; but sphagnum did not give good results
as regards either stands or growth of the solanaceous plants, pepper, eggplant,
and tobacco.

Chemical Soil Surface Treatments in Hotbeds for Controlling Damping-off
of Early Forcing Vegetables. (W. L. Doran, E. F. Guba, and C. J. Gilgut.)
This study w^as completed with the publication of Bulletin 394.

In some additional tests, certain newer chemical materials offered as seed pro-
tectants, notably Spergon, Thiosan, yellow cuprous oxide, and tri-basic copper
sulfate, showed in many instances value equal to or surpassing Semesan, red Cu-
prous oxide, and zinc oxide on a wide variety of flower and vegetable seeds.

Control of Greenhouse Vegetable Diseases. (E. F. Guba, Waltham.) The
various types of tomatoes studied for their reaction to Alternaria early blight
were also tested for their susceptibility to Cladosporium leaf mold. Among them
seven types were found showing a very slight degree of susceptibility indicated by
sparse, yellowish areas without sporulation, molding, or necrosis, and one type
showing none of these symptoms and from all appearances immune. In addition.



ANNUAL REPORT, 1942 21

all six selections of Lycopersicon peruvianum (L.) Mill, showed a similar type of
immunity. Bulletin 393 embodies the progress and results of several years' work
in the development of resistance in tomatoes to Cladosporium. The Bay State
variety is showing susceptibility to the new strain of Cladosporium in an increas-
ing number of greenhouses. Nevertheless, many growers have accepted the new
variety as a choice forcing tomato. Now that resistance to the new or Bay State
strain of Cladosporium has been found, it is being utilized in an effort to combine
resistance with desirable commercial type.

Resistance to Tomato Alternaria Early Blight. (E. F. Guba and R. E. Young,
Waltham.) Seed of some 37 elementary types of tomatoes offered as possessing
significant resistance to Alternaria solani (E. & M.) Jones & Grout were secured
for trials at Waltham. These tests were purely exploratory, and if suitable re-
sistance appeared, it was the intention to utilize it for breeding purposes in the
development of a blight-resistant tomato. Since a large volume of copper fungi-
cides is employed in the control of tomato early blight, this stud}- would appear
to represent a worthy contribution to the war effort.

Weather conditions were ideal for the development of early blight, but in spite
of repeated artificial inoculations the disease rather consistently became epi-
demic only in correlation with a heavy load of fruit and maturity of the fruit.
Thus many types remained relatively free of the disease until late m the season
and then showed it in severe proportions. The largest and heaviest fruited and
earliest maturing types consistently showed a high degree of susceptibility, and
only nine types showed resistance.

Interrelation of Wettable Sulfur, Lead Arsenate, and Lime in Apple Spraying.

(Departments of Botany, Chemistry, Entomology, and Pomology cooperating.)
This project is intended to add to our knowledge of insect and disease control and
to assist in making improvements in the apple spraying schedule. On this basis
special consideration was given to tenacity of sulfur, scab control, spray injury,
and insect control.

Disease Resistance and Heredity of Carnations. (E. F. Guba cooperating
with H. E. White, Waltham.) Eighteen varieties of carnations were scrutinized
for their susceptibility to various important fungus diseases. As was to be ex-
pected, in view of the wide host range of Rhizoctonia solani, no resistance to this
fungus was found.

Twenty-two varieties were studied for their reaction to Alternaria dianthi
(blight). Virginia, New Deal Ward, Minna Brenner, and Hazel Draper
showed a moderate to high degree of susceptibility, but not until long after the
benching season. The disease has become increasingly insignificant in recent
years.

A high degree of susceptibility to Uromyces rust was shown by Woburn, Oli-
vette, New Deal Ward, Hazel Draper, Paragon, Pink Treasure, Johnson's Crim-
son, Spectrum Supreme and King Cardinal.

Tests with the branch rot organism, Fusarium dianthi, and the root rot or-
ganisms, F. avenaceum and F. culmoriim, yielded no results.

Effect of Soil Temperature on Timothy (Phleum pratense L.). (L. H. Jones.)
Seedling plants of timothy were transplanted to containers of soil at a high level
of fertility. The plants were allowed to establish themselves at a soil temperature
of 65° F., after which the apparatus was adjusted to a range of soil temperatures
from 50° to 90° at 10-degree intervals. Tiller counts at 50 days showed that soil
temperature affected stooling, the number being greater at 70° and tapering off
to the extremes of 50° and 90°. At 50° there was a marked tendency for the shoots
to be prostrate in habit. This prostrate habit was also noted in a cool greenhouse



22 MASS. EXPERIMENT STATION BULLETIN 398

with brome grass {Bromiis inermis Leyss.), meadow fescue (Festuca elatior L.),
perennial rye grass {Lolium perenne L.), and timothy (Phleum pratense L.).

The number of tillers was closely associated with the height of the plants, those
at 70°F. being the tallest at 50 days. Foliage and stem color were affected by sol
temperature. The plants at 50° were a dark green, and those at 60° were inter-
mediate between the dark green at 50° and the light green at 70° and above.

There were enough replications so that half the containers were available for
shifting of temperatures, the remaining half being kept at the same temperature
as at the start of the test. The shifted temperatures were 20 degrees higher or
lower than the original temperatures. By this means it was possible to corrob-
orate the earlier conclusions made at the 50-day period. Plants which had been
at 50° F. and were dark green, prostrate in habit, short, and with few tillers, re-
sponded soon to the 70° soil temperature by assuming the characteristics of the
check at 70°. On the other hand, the plants at 70°, when shifted to 50°, became
prostrate in habit, dark green in color, and stopped growing. At temperatures
of 80° and 90°, the check plants and those shifted from 60° and 70° were not in a
healthy state of activity; but the unhealthy plants shifted from 90° to 70° and
from 80° to 60° resumed the healthy appearance of the check plants for these
temperatures.

In the final stages, the plants at 90° F. soil temperature were very poor. Sev-
eral had died and the remainder were stunted and dark green in color. The
plants at 50° and 60° had the most and tallest spikes, but the foliage at the base
was sparse. The plants at 70° had thick foliage at the base indicating continued
vegetative activity. These plants also had the greatest dry weight. It also
appears that soil temperatures lower than 70° give greater dry weights than those
above 70°. Since careful attention was given to supplying water, the experiment
indicates that soil temperature is the governing factor, and not drought, which
is frequently associated with long hot spells of weather.



DEPARTMENT OF CHEMISTRY
Walter S. Ritchie in Charge

Chemical Investigations of the Onion. (Emmett Bennett.) The preliminary
work on the characterization of the soluble carbohydrates of the Ebenezer onion
as reported last year has been extended. The titration of the hydrolyzed sugars
with standard iodine and alkali and the determination of the fructose both indi-
cate that the total sugars are approximately two-thirds d-fructose. Syrups of
the total hydroh zed sugars yielded crystals with a specific rotation of [-41°Jd,
which is of the order expected for a mixture of d-glucose and d-fructose in the
ratio of 1 to 2.

By removal of the reducing sugars, a preparation was obtained having a
specific rotation of about [+48°Jd, and after inversion about L-17°Jd. This,
together with the large negative enhancement noted on solutions after inversion,
is a strong indication that the chief non-reducing sugar is sucrose.

The present work is concerned with metabolic changes which occur in the cell
during growth. Samples were taken at intervals during the growing season. At
mid-season onions were collected and divided into equal groups, some of which
were placed in total darkness for different periods of time. The many forms of
nitrogen have been determined as well as the sulfur compounds, organic acids,
and carboyhdrates.



ANNUAL REPORT, 1942 23

Some of the chemical changes during normal growth are as follows: Total
nitrogen and organic acids decreased as the season progressed; soluble nitrogen
and total sugars increased. The increase in total sugars continued until the
middle of the season. Up to that time the trend was the same for both reducing
and non-reducing sugars; thereafter the main change appeared to be the formation
of non-reducing sugars.

The results of the culture work in complete darkness are almost completely
opposite those of the control. In darkness the content of solids, total nitrogen,
water soluble nitrogen, organic acids, and carbohydrates decreased gradually.

The Hemicelluloses of Forage Plants. (Emmett Bennett.) Previous work at
this station has indicated that a considerable difference exists in the content of
moisture of forage grasses. An investigation of the polyuronide hemicelluloses of
two species, sheep's fescue {Festuca ovina) and sweet vernal (Anthoxanthum
odoratum) which represent grasses of low and high moisture content respectively,
indicated that this difference may be due chiefly' to this group of substances. The
greater content of total hemicelluloses was found in the low-moisture grass, and
the nature of these groups in the two species was quite different.

The hemicelluloses of each species, when hydrolyzed, yielded mainly a uronic
acid, 1-arabinose and d-xylose in the approximate molar ratio of 1:0.2:15.7 in
sheep's fescue and 1:2.9:9.3 in sweet vernal. A preliminary examination of the
viscosity of the hemicelluloses indicated that those from sweet vernal grass when
dispersed in water produced not only the more viscous system, but also the more
stable system. Those from the sheep's fescue for the same period and under the
same conditions were almost completely flocculated. It would appear, there-
fore, that the degree of hydration of the two products differs considerably, and
that the species containing the more highly hydrated product has the greater
original moisture content and contains the larger percentage of 1-arabinose,

Lignin and Its Relation to Absorption of Minerals by Plants. (Emmett Bennett.)
Special attention has centered around the mobilizing power of isolated lignin as
a representative of the residual organic matter in the soil. While it is known that
organic matter may absorb free ions in the soil, its role as a mobilizer of ions is
not so well established. To determine the possibilities of lignin in this capacity,
a container was devised which would hold both the inorganic material (calcite)
and the suspension of lignin in contact with each other and allow the suspension
to be agitated \\ith a power driven stirrer, to renew the contact, without disturb-
ing the calcite. The lignin was freed from mineral acids by electrodialysis. The
extent of mobilization could be noted from time to time by the losses in the
weight of calcite. Calculations based upon such a procedure indicated that
mobilization did take place over a period of several months in amounts equivalent
to a base exchange capacity of about 175 milli-equivalents per 100 grams of lignin.
This phenomenon indicates that the residual organic matter as such may mobilize
ions from insoluble compounds. A practical application may be in the form of
contact depletion.

On the assumption that the high base exchange values of soil organic matter
are due to previous oxidations, samples of lignin were oxidized by iodine. Iodoform
was obtained as one by-product. The oxidation value amounted to 175 ml. of
N, 10 iodine per gram of lignin. Base exchange values of the oxidized lignin were
about 35 percent higher than those of the control.

Attempts were made to determine the nature of the functional groups most
active in base exchange activity by blocking the aromatic hydroxyl group with
acetyl groups. This, while not wholly satisfactory, indicated that the hydroxyl
groups were chiefly responsible.



24 MASS. EXPERIMENT STATION BULLETIN 398

Chemical Changes in Cooking Quality of Vegetables. (Monroe E. Freeman.)
A quantitative method for measuring the texture of baked potato tissue by esti-
mating the pore space of dried slices was found to be satisfactory. The method
was applied to the study of texture changes in tubers during winter storage.
Samples stored at 35° and 50° F. for 76 days, 130 days, and 161 days were baked
and the texture was measured or estimated by three methods. Center rot and
"blackening" appeared in so many tubers that conclusive results were not ob-
tained. From the sound samples available, however, there seemed to be very
little change in specific gravity during the storage period. A visual scoring method
indicated that the cooking quality, i.e., texture, was lower in tubers stored for
longer periods and at the lower temperature. Toluene index of the tubers indi-
cated a small decrease in baking quality with time of storage at the higher temp-
erature, but because the samples were incomplete these results cannot be assessed
with any certainity.

Physico-Chemical Properties of Starches. (Monroe E. Freeman.) The
anomolous heat capacities of starch-water systems reported in 1941 were care-
fully studied and applied to dextrin-water systems and to sand and water. The
data allowed a clear explanation of the phenomenon and its relation to the bound
water in lyophillic colloids and indicated the existence of a general phenomenon
of lyophillic systems that hitherto has not been clearly recognized.

The Influence of Base Exchange Capacity and of Exchangeable Ions in Massa-
chusetts Soils on the Availability of Potassium. (Dale H. Sieling.) Pot cultures
of synthetic soil for plant growth were prepared by mixing quantities of a typical
tobacco soil, the Agawam fine sandy loam, with electrodialyzed bentonite which
had been adjusted to fixed calcium levels with calcium hydroxide. These cultures
were all of the same reaction and varied considerably in their base exchange ca-
pacity. Four levels of base exchange capacity, 7.1, 12.0, 17.0, and 22.0 milli-
equivalents per 100 grams, were established. At each base exchange capacity
level the soils were fertilized with four different quantities of potassium and with
a fixed quantity of both phosphorus and nitrogen. Nitrogen was also added at
various times during the growth of the plants. Each culture was prepared in
duplicate and contained 7000 grams of synthetic soil. Tobacco, Havana Seed
211, was used to test growth response and nutrient uptake. One plant was grown
in each culture and the soils were watered with distilled water whenever the rain-
fall was inadequate.

Luxuriant growth was obtained in all cultures and there were no apparent
nutrient deficiencies or e.xcesses. Growth, as indicated by the dry weight of the
plants, was increased very little by addition of gypsum. The cultures having an
exchange capac't}' of 17.0 m



Online LibraryMassachusetts Agricultural Experiment StationBulletin - Massachusetts Agricultural Experiment Station (Volume no.379-398) → online text (page 71 of 77)