Circular [Feb. 1912]

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GEORGIA STATE BOARD
OF ENTOMOLOGY
E. L. WORSHAM,
State uto_loJist

GENERAL L\6RP\R'l

CIRCULAR No. 11

OCT 211939

UNNERSITY Of GEORG\~

FEBRUARY, 1912

WILT DISEASE OF COTTON
AND ITS CONTROL WITH
SUGGESTIONS ON SEED SELECTION

BY
A. C. LEWIS,
Assistant State Entomologist

WILT DISEASE OF COTTON IN GEORGIA AND ITS CONTROL
WITH
SUGGESTIONS ON SEED SELECTION
BY
A. C. LEWIS, Assistant State Entomologist
INTRODUCTION.
Wilt disease of cotton is the most serious enemy to the cotton plaut, at present, in Georgia. . The annual loss last year from this disease, based on what information we have been able to secure, was at least $1,000,000.00. The worst feature about it is that the disease is spreading over the state very rapidly and the loss wlll increase each year unless the resistant strains of cotton are planted in the affected fields. It this is done and the recommendations given in this circular are followed, this loss may be greatly reduced.
Distribution.
Wilt disease of cotton occurs in the following states: Alabama, Arkansas, Louis iana, Mississippi, Missouri, Oklahoma, Texas, North Carolina, South Carolina, Tennessee, Florida, and Georgia.
In Georgia, the disease exists in every county south of Macon, and in a few coun ties in North Georgia.
Symptoms of the Disease.
The first outward symptom of wilt is generally a wilting of some of the leaves and branches, hence the name "wilt." Many of the young plaRts die within a few days after the first external symptoms of the disease appear, which is usually when they are about six weeks old. Plants will continue to die from time to time until frost. Some of the plants attacked may partially recover from the disease and put out branches near the ground, but as a rule these branches do not produce much cotton.
The internal symptoms of this disease are very characteristic, so that it ill not dimcult to tell wilt from any other disease to which cotton is subject in Georgia. It the roots and stems of a diseased plant are examined after cutting lengthwise, it wIn he found that the woody portions are black or much discolored. This is the symVUlDl rhat has given the aisease the name "blackroot."
s

The Cause of Wilt.
The cause of the cotton disease commonly called "blackroot" or "wilt" is a (Fusarium) funglols, which enters the roots and stems of the plants. During the winter the disease lives on the decaying cotton roots and stems in the soil, mainly in the form of spores, the spores corresponding to the seeds of the higher plants. In the spring, when the cotton begins to form rootlets and roots, these are affected by the fungus. The fungus penetrates the roots and grows up into the stem, following the water ducts and plugging them with mycelia or threads of the fungus. This prevents the upward fiow of sap from the roots, thus cutting off the food supply and stunting or killing the plant.
Plants Attacked by the Fungus.
So far as known, cotton, okra and perhaps the wild coffee weed are the only plants the wilt fungus lives on as a parasite. In some parts of the State, cowpeas wilt and die in much the same way as cotton. This disease is caused by a fungus which is closely related to the fungus that attacks cotton. On infected land the Iron or Brabham cowpea should be planted, as they are very resistant to this disease. The watermelon wilt is a similar fungus disease and should be fought by rotation of crops and the planting of resistant seed. Prof. W. A. Orton, Bureau of Plant Industry, United States Department of Agriculture, Washington, D. C., has by hybridization secured a strain of . watermelon that is quite resistant to this disease.
Conditions Favorable 0 the Disease.
Some seasons the wilt disease is worse than in others. This may be due to one of two causes. viz., the weather conditions or the number of nematodes in the soil, or both. Thus it has been observed that the disease is more severe during a wet season than in a dry one. While it Is true that wet weather is favorable, and dry weather unfavorable, to the disease, weather conditions, such as heat or cold, have never been known to exterminate the fungus.
Nature of Soil Infected
A few cotton growers in Georgia have thought that diseased land was deficient in some necessary element or elements of plant food. To determine this. we had Dr. Edgar Everhart, Chemist of the Georgia Geological Survey, to analyze a sample of lIoil taken from a diseased field at Zeliabee, Georgia. His analysis showed that the soil was not deficient in any element necessary for plant growth, except lime, contain ing only .047 per cent of lime. As noted elsewhere, the addition of lime to this sol1 did not reduce the severity of the disease.
The nature of the soil, whether sandy. or clayey, seems to govern in a large meas ure the distribution of the disease in Georgia. It has been observed that the disease is more severe in the loose. sandy soils of South Georgia. Thus the sample of soil we had analyzed contained a very large per cent of sand or silica, 90 per cent. The worst alrected spot in a field is usually the lowest place where the sand is washed in, form ing a very loose. sandy soil. The disease has never been found on the clay soils of Georgia. except in a few instances. The fungus causing the wilt disease of cotton may be looked upon as a weed indigenous to some soils, and like weeds. thriving best on eel" tain soils.
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Rotation of Crops.
As the fungus causing the wilt disease of cotton attacks only cotton and okra, it follows that planting the land in other crops will slowly starve out the fungus. Thus far, however, all attempts have failed completely to eradicate the fungus from the soil of infected fields, even with a rotation of ten years. Rotation of crops is important, however, in the control of the wilt disease on account of the nematode worms. For a full discussion of this subject see paragraph on page 6, Relation of Nematode WOi'ms to Wilt.
Date of Planting.
Many planters have thought that late planted cotton is less injured by wilt than early planted cotton. This opinion had been quite prevalent among planters of Beuna . Vista, Ga., until one of their number, Mr. J. B. Simons, had a late planted crop in 1905 that died very badly. Mr. Simons' experience is particularly interesting on account of the fact that he not only planted late, but planted on land that had been in other crops during 1903 and 1904. The field was planted on June 3, 1905, following a crop of winter rye. Over 90 per cent. of this cotton died from wilt. In 1908, at Vienna, Georgia, cotton planted after oats died very badly. In our experiments in 1905 one plat of cotton was planted April 18th, and another June 5th. Over 75 per cent. of the cotton died on each plat. From these experiments and observations it is apparent that late planting can not be depended upon as a remedy for the wilt disease of cotton.
Non-Effect of Fertilizers.
While many cotton growers are of the opinion that the continued use of commer cial fertilizers is responsible in a great measure for the severity of the wilt disease of cotton, others are just as sure that it can be controlled by the use of certain fertilizers, especially muriate or sulphate of potash. To settle this point, we began in 1905 to test different fertilizers to see what effect, if any, they would have on the disease.
From our experiments it is evident the disease can not be controlled by the use or disuse of commercial fertilizers. In our experiments even kainit, when used in large quantities, 800 pounds per acre, was of no benefit in controlling the disease.
Some farmers have reported to us that the use of stable manure increased the disease. This could only happen where the barn yard had become inoculated with the [ungus from infected soil or cotton stalks, for as a rule, manure is a good fertilizer for cotton.
Non-Effect of Fungicides.
OUI~ experiments and those conducted by Prof. W. A. Orton show that fungicides, such as Bordeaux mixture, copper sulphate, copper carbonate, liver of sulphur, formalin, sulphur, sulphur and lime are of no value in controlling the wilt disease of cotton.
Comparative Resistance of Different Varieties of Cotton.
In our e?rperiments we have tested so far 54 varieties of cotton, to see if we could find a variety that would be resistant to the wilt disease of cotton. The different varieties showed great variations in resistance to the disease, but none of them was resistant enough to be worth propagating for this purpose. In all but one of the varieties, namely, Red Shank, 50 per cent. or more of the cotton died from the wilt disease. While the
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R.ed Shank was somewhat resistant, 45 per cent. dying, it was discarded on accounl af its poor yield.
Of the long staple cottons tested, only one, the Egyptian Mitafifi, showed any marked resistance, and this variety is not well adapted to Georgia conditions.
There are now a number of resistant strains of cotton that have been developed by selection, and on diseased land it will not pay to plant any other variety of cotton.
Relation of Nematode Worms to Wilt. Many farmers in Georgia know from dear experience that cotton frequently dies very badly when planted after common cowpeas. That this is due to the fact that the cowpea increases the number of nematodes in the soil, and that their presence in the cotton roots weakens the plants and increases the severity of the wilt disease of cotton. is well known. The nematode worm, Heterodera radicicoia (Greff. Mul.) is a parasite which infests the roots of many plants, and causes the knots commonly known as nematode galls or root knots. Affected plants are very much stunted and sometimes killed. A few weeds
Fig. 1. Nematode galls on cotton roots. Original. and a great number of cultivated plants are subject to attack by the nematode worms The most common of these in Georgia are: Cotton, cowpeas (all varieties except the Iron and Brabham), watermelon, cucumber, cantaloupe, sugar cane. okra, cabbage, collard, potato, tobacco, mulberry, peach and fig. Fig. 1 shoy;s nematode galls on cotton roots. In addition to the above, Prof. Atkinson mentions the following plants as being badly affected in .Alabama: Citron, bird's foot clover (Lotus corniculatus), rutabaga, parsnip, and salsify. In Farmer's Bulletin No. 333, Prof. W. A. Orton mentions the following weeds as being subject to attack by the nematode worms' Purslane, pigweed (Amaranthus), "May-pop," "Indian potato," and "Saw brier." Prof. Orton also states that "Bermuda grass, chufas and summer oats are slightly susceptible. but probably can be used in rotation when root knot is only slightly pre:valent."

Fig. 2. Nematode galls on roots of Unknown cowpea. Original .

Fig. 3. Roots of the Iron cowpea, free from Nematode galls. Original.

Rotation of Crops for Controlling the Nematode Worms.
The rotation of crops for controlling nematode worms is so important that we w1Jl give in detail some of our observations and experiments along this line. In 1905, Col W. D. Hammack, of Coleman, Georgia, had a field of cotton that well illustrated tb result of planting cotton after the common cowpea. In 1903, the field was planted in 'Cotton and the cotton nearly all died with the wilt disease. In 1904, the qeld was planted in corn and common cowpeas, two rows of corn and then a row of cowpeas. In 190r, the field was planted in cotton. Over 75 per cent of the cotton died in the rows thaI bad been in cowpeas, while in the rows following the 'Corn only 25 per cent of the cotton died. At Vienna, Georgia, on Mr. Ed Howell's place, a field was sown in oats in the fall of 1906. The next summer, after the oats were cut, part of the field was sown ill Unknown cowpeas. In the spring of 1908 the whole field was planted in Dillon ano Dixie resistant cotton. The cotton planted after the cowpeas died very badly, in spots. from 25 to 50 per cent., while in the other part of the field not over 10 per cent. to If> per Cent. died from wilt.
In 1909, in our experiments at Vienna, Georgia, on Mr. Ed Howell's plantation, a plat of land was planted in the Iron cowpea, on which in 1908 over 75 per cent of the

Fig. 4. On left, cotton after cotton; on right, after Iron cowpea. For details see above paragraph. Original.

Dillon 'Cotton died from the wilt disease and nematode worms. This land was ver.'oadly infested with the nematode worms as was shown by the numerous galls on the roots of the Unknown cowpea, a few of which were growing in the fields. Fig. 2eshowp nematode galls on roots of Unknown cowpea. On both sides of the plat cotton was planted in 1909. In 1910, the different plats were all planted in the same variety or 'Cotton, the Modella, a resistant strain. The results were as follows: About 5 per 'Ceat. of the cotton died in the plat planted after the Iron cowpeas, while on the other plats planted after cotton, from 50 to 90 per 'Cent. of the cotton died. The difference betw~en the two plats is well shown in Fig. 4. In 1909, we also carried on a similar ~xperiment on Col. M. B. Council's plantation at DeSoto, Georgia, with almost as markeo results.
In comparison with this we would call attention to a field that had been plantea 1n oats and the Unknown cowpea for three years. In 1910, the owner planted it in cot

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ton just to see what the cotton would do. The result was that nearly all the cotton

died where the nematode worms and wilt were present. In a part of the field no wilt

disease was present, but the nematode worms were very numerous and here the cotton

was much stunted, and it also "rusted" very badly. In July, 1910, the writer visited Mr.

J. p. Coffee's plantation near Valdosta, Georgia, to examine som~ of his cotton that was

not growing well. A careful examination of the cotton roots showed the presence of

n~matode worms. The small feeding roots were all rotted off and small nematode

galls were found on many of the roots. ear a patch of sugar cane the cotton roots

showed numerous nematode galls, as shown in Fig. 1. About ten acres of cotton were

badly stunted by the nematode worms but not so much of the cotton was dead, as there

was not much wilt disease present. Later the writer was informed that the ten acres

made a little over two bales of cotton.

Whether the cotton is suffering from the wilt disease or the nematode worms, or

both, .can be determined by examining the roots. The nematode worms do not always

produce large galls like those shown in Fig. 1, but the small feeding roots are nearly all

destroyed. If the wilt disease is present, the roots and stem near the ground will be

black inside in the woody portion.

These observations and experiments have been given in detail in order to impress

upon the cotton growers the importance of rotation of crops in controlling the nematode

worms and wilt disease of cotton. There are many fields of cotton in the State, like

the last one mentioned above, that are much stunted and the yield greatly reduced

on account of nematode worms and wilt. These fields could be made to yield a bale

to the acre by a proper system of rotation and the planting of a resistant strain of cotton.

The following crops may be used in rotation, as they will not support the wilt fungus

nor increase the number of nematode worms in the soil: Corn, wheat, rye, oats, Iron or Brabham cowpeas, velvet bean and peanut.

We cannot too strongly advocate the planting of Iron or Brabham cowpeas on land

infested with nematode worms. In the above and other experiments we failed to find

I

any nematode galls on the roots of these cowpeas. The roots of the Iron cowpea are shown in Fig. 3. In Fig. 2 the roots of the Unknown cowpea are shown. Notice the galls on the roots of the Unknown cowpea.

Difference Between Nematode Galls and Nitrogen FiXing Nodules.

The nitrogen fixing nodules are mistaken by some for nematode galls. The nitrogen fixing nodules appear on the roots as small shot-like bodies, external to the root and easily detached from it, as shown on the peanut roots in Fig. 5, on page 14. When nematode worms attack the roots they cause swellings and distortions of the same, as shown in Figs. 1 and 2, and these cannot be pulled off without breaking the roots.

Selection of Seed from Resistant Plants.
a doubt many cotton planters have noticed that in a badly wilt affected area where nearly all the plants die, or are much stunted, there may be a few plants that are apparently thrifty and resistant to the disease. Evidently these plants are exposed to the disease to a greater or less extent, bt.t do not succumb from some inherent cause.

METHODS OF SELECTING SEED.
Mass.
Some cotton growers make a practice of going through their fields, picking cotton [rom the best stalks, and planting the seed to improve their cotton. By continuing this process year after year the cotton may be improved. to a certain extent. Our expe-
n

riments and others show, however, that mass selection is a very poor way to secure a resistant strain of cotton, and that even when working for yield alone, individual selection is the better method to use.
Pedigree Breeding, or Individual Selection.
In individual selection, or pedigree breeding, a number of the' best and most resistant plants are selected, and the seed of each plant saved to itself. The next season a shorl row is planted from each stalk. The rows are planted side by side and this gives a good opportunify for comparing the progeny from the different stalks and finding out which selection is the most resistant and has the strongest transmitting power. This is an important point to determine, for it has been found that plants, like animals, vary greatly in their power to transmit certain qualities to their progeny. Thus ten stalks may be selected which to all appearances a~e resistant and the progeny rows the next season will show a great variation in resistance to the disease. If anyone of the pro geny rows shows great resistance and a good yield, it is saved to itself an.d plantecl the next season in a multiplying patch. The seed from this in turn is saved and the following season as many acres as possible are planted with it. From this it 'will bp seen that from one stalk In three years a large quantity of seed may be secured.
(For a more detailed discussion on individual selection, see page 12.) By this method we have secured several strains of cotton that are quite resistant t~ the wilt disease.
Hybridizing, or Crossing Varieties.
Another method of improving cotton Is by hybridizing or crossing one variety with another. In doing this the pollen from one variety is transferred to the pistil of the other variety. To do this, you proceed as follows: Select the plants of the different varieties you wish to cross. In the evening when you can tell which blooms are going to open the next day, emasculate the blooms on the plants that you wish to bear the bolls. To do this, take a small pair of scissors and carefully cut off the petals, the colored part of the flower, then clip off the stamens that surround the pistil. ThE' Stamens are arranged around the pistil which Is in the center of the flower, and bear the pollen sacks. In cutting off the stamens be sure and not to injure the pistil. After removing the stamens, cover with a small paper sack. Cover the blooms on the se !.ected plants of the other variety with a small paper sack, so as to keep insects away The next morning after the blooms are open, take this covered bloom and dust the pollen from it onto the pistil of the other variety that you emasculated, and cover witb a paper sack. In two or three days this pa1>er sack should be removed. It is well to select stalks for this purpose that will have three or four blooms the next day, as on1) the hybridized bolls on the same stalk should be saved together. Each hybrid should be numbered and brief notes made on the different parent plants. In 1905, I begau crossing different varieties of cotton with th; Dixie and Dillon to see if I could secure a more resistant and earlier strain of cotton. One of these hybrids, a cross of King'!' improved with the Dillon, is very promising. While this hybrid Is not so early as the King, it is earlier than the Dillon. In a year or two we hope to have seed of this hybrid for distribution.
In our variety test it was noted that the Egyptian cotton, the Mitafifi, was mucb more resistant to the nematode worms than any other variety. In 1906, the Dixie waF crossed with the Mitafifi to see if we could secure a strain of cotton that would be very "esistant, both to the nematode worms and the wilt disease of cotton.
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In our progeny rows this season, 1911, some of these hybrids showed great resist ance to the nematode worms and wilt. One row, which was very resistant, also haa a very good staple. We think this one of our most promising hybrids. Our hybrids with the early varieties are not a success yet, but we hope some of them may be of value.
The Mexican Cotton Boll Weevil and the Wilt Disease of Cotton.
That dreaded enemy of cotton, the Mexican Cotton BolI Weevil, is not in Georgia yet but it is coming at the rate of 50 to 75 miles a year, and may reach here in two or three years. The best way to fight this insect is by certain cultural methods and the planting of very early varieties of cotton. The early varieties, such as King, Simpkin and Tri umph, are very susceptible to the wilt disease, hence we must develop an early strain of resistant cotton. For the past three years we have been making a number of selec tions of the most resistant plants from King and other early varieties of cotton, but so far none of these has proven to be very resistant.
We are now endeavoring, by the method of selection, to increase the earliness or the resistant strains. Last season, in one of our resistant strains, the Mode'lla, there were a number of stalks that were much earlier than the others. A number of these stalks were selected and the seed planted last spring.
These rows were earlier this season than the Modella rows. One row planted April 18th, had open bolls on August 10th, or 122 days from planting.
Distribution of R,esistant Cotton Seed.
The object of the work and experiments on wilt is two fold: 1st, to secure strains of cotton that are resistant to the disease; 2nd, to propagate these resistant strains 01 cotton and distribute the seed to the cotton growers who have to contend with the disease. This season we hope to be able to furnish each applicant one bushel of seed. The seed will be sent by freight or express, the party receiving the seed to pay the charges. If we can secure a special express rate, as heretofore, the express will be only one cent a pound anywhere in the state. Parties wishing to secure five or more bushels of seed, may secure it on the co-operative plan (described below) at one dollar per bushel.
CO-OPERATIVE WORK WITH THE BUREAU OF PLANT INDUSTRY ON THE
WILT AND ROOT KNOT DISEASES.
We are frequently asked the question, "Will the cotton maintain its resistance more than one year?" lOur reply is, "Yes, if it is kept pure." The great trouble with most farmers is, that when they receive the seed they plant it beside other varieties, and plant the seed year after year without making any selections and without roguing out dis eased and undesirable plants, and without using due care in ginning the cotton. Under these conditions the resistant cotton will not maintain its resistance many years.
To encourage the farmers to engage in the improvement of the resistant strains of cotton and cowpeas, which they may receive from the State Board of Entomology or the Bureau of Plant Industry, the Georgia State Board of Entomology is now working in co-operation with the Bureau of Plant Industry for the furtherance of the above mentioned objects. Under this plan the State Board of Entomology or the Bureau or Plant Industry agrees to furnish, or make available for purchase by the grower, at $1.00 per bushel, 5 to 25 bushels of seed of one of the resistant strains of cotton, grown under our supervision, and if possible, also the Iron and Brabham cowpeas at the market price.
We wish to thank Prof. W. A. Orton and Prof. W. W. Gilbert.. of Wasbiugton. D. C., for ..aluable suggestions giveo io preparing tbis circular.
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The co-operating grower must, in return, agree to improve the cotton annually by making a number of individual selections and test each by the progeny row and in crease plat method of breeding. 'This method is described in detail on page 10. The form of agreen ent which each grower will be required to sign will be found on the last page of this circular. This may be used in making an application for seed under this plan. From time to time the representative of the Board and Department will visit the co-operative breeders and give advice and suggestions.
Suggestions on Making Individual Selections.
In making individual selections great care should be exercised in order to secure the best plants. In a row or field of the same variety of cotton it will be noticed that the different plants vary greatly in many characters. In determining which individual plants should be selected the following characters should be carefully studied: Resistance to wilt, root knot and anthracnose; fruitfulness and earliness; percentage, lengtb and strength of lint; type of plant and distribution of fruit on plant.
1st. Resistance to Wilt.
In order to be sure the disease is present in the soil where the individual selectioU!! ale made, it is well to plant the cotton where, the year before, ordinary cotton died very badly.
Where the ordinary cotton died the worst, is the best place to make the selections from the resistant strains. If the resistant cotton dies more in one place than another, make the selections where the cotton dies the most. Be sure, though, to select the most resistant plants. Do not select stunted plants that have recovered from the effects 'of the disease, even if they are well fruited, as the progeny from such stalks will be very susceptible to the disease.
2nd. Resistance to Root Knot, or Nematode Worms.
The nematode w\lrms, as mentioned on page 6, do a great deal of damage to cotton by stunting its growth, and killing it if wilt is present. While the nematode worms may be starved out by rotation 01 crops, a strain of cotton that would be resistant to both wilt and root knot would be valuable. The wilt resistant strains are somewhat resistant to root knot and we believe, by continued selection of the most resistant plants this quality may be greatly improved. Select the stalks that are not stunted, as these are resistant.
3rd. Resistance of Anthracnose.
Some seasons this disease does a great deal of damage, in cases, as high as 50 per cent. of the bolls rotting. All varieties are more or less susceptible to anthracnose. At present the best way to control this disease is by rotation of crops, use of resistant varieties and seed selection. A plant badly affected by anthracnose should not be selected even though it is very resistant to wilt and very well fruited. Only plants free or nearly free from the disease should be taken for seed.
4th. Fruitfulness.
This quality should be carefully considered, as we want the yield per acre to be as large as possible. While the resistant strains are now as fruitful as most varieties, this quality can be improved by careful selection of the most fruitful plants. If you have a uniform stand it is easy to select the IJ'ost fruitful stalks by comparison.
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5th. Earliness.
In order to raise cotton under boll weevil conditions, a~ previously mentioned, we must plant an early resistant strain of cotton. There are two ways of securing an early resistant strain: 1st, by crossing the wilt resistant strain with early varieties; 2nd, by selecting the earliest plants from the resistant strains we now have. Judging from our experiments (given on page 8) we believe individual selection of the earliest plants will be the quickest and best method by which to secure an early resistant strain.

6th. Length, Strength and Per Cent. of Lint.

While in the upland cotton the length of the staple is not so important as in the long staple, still, if it is too short and weak, it will not make a good sample. The staple
should not be less than % of an inch long, and it is much better to have it an inch or
1% inches long. The strength of the staple can be tested by hand, only in a general way, but as a rule this is all that is necessary.

The per cent. of lint a variety of cotton will yield is an important character. In

the field the per cent. of lint can be determined only In a general way by observing how

well the seeds are covered by the lint. The per cent. of lint each selected stalk yields

should be determined. In order to gin a single stalk it Is necessary to have a hand gin.

Such a gin of ten saws is manufactured by the Eagle Gin Co., Bridgewater, Massachu

setts, and sells for about $50.00. All stalks that yield lejls than 331f.l per cent. of lint

should be discarded. In our work we discard all that yield less than 34 per cent. of lint.

For more details on this subject, write A. C. Lewis, Assistant State Entomologist, At

lanta, Georgia.

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7th. Type of Plant.
In almost every variety there is a certain type of plant that predominates, but other types will also be present. Stalks of the predominating type should be selected if they are as resistant and well fruited as the other type, as the individual characters will be more likely to be transmitted to the progeny.
It Is well to have the form of an ideal stalk well fixed in your mind, and make your selections accordingly. Keep your ideal before you from year to year. Don't select one tYPe of stalk this year and another the next, unless you make your selections from a different strain of cotton, or you will not make much progress In fixing your type of cotton.
The best stalks to select are those having long fruiting limbs close to the ground, and with short Internodes, or the joints close together. The fewer. large stalky branches a stalk has, the better, providing the fruiting branches are more numerous.

8th. Distribution and Arrangement of Fruit Over the Stalk.
If a number of cotton stalks are carefully examined it. will be noticed there is a great difference in the way the fruit Is distributed over the plant. As a rule, it Is best to select the plants that have most of the fruit on the lower part of the stalk, for such begin fruiting early.
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Roguing.
To maintain the resistlmt quality, roguing should be practiced in the progert) rows and increase plots, and also in the field. That is, the diseased and stunted stalk~ should be cut out about July 1st and August 1st, to prevent crossing with the resistant plants and thereby reducing their resistance. In the progeny rows and increase plots this should never be neglected. If the diseased stalks are not removed from the field, they should be picked to themselves before the cotton is gathered.
Ginning the Seed.
The individual stalks and the progeny rows should be ginned on a hand gin. Gig the field of resistant cotton on a private gin, if possible. If the cotton is ginned on a public gin, see to it that the seed is all removed from the breast of the gin and other parts before the cotton is run through. Let the seed drop on the floor, or better, on a sheet; never run it through the seed carrying auger.
Distance to Plant.
As the stalks of the Dixie and Modella cotton are large, branching and spreading, to secure the best results the cotton should not be planted too close. With rows 4 to 4% feet apart plant 2 to 3 feet apart in the row, and thin to one stall, in a place,
Fig. 5. Nitrogen fixing nodules very numerous on Peanut roots. Original.
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MEMORANDUM OF UNDERSTANDING BETWEEN THE UNITED STATES [JEPART

MENT OF AGRICULTURE IN CO-OPERATION WITH THE GEORGIA BOARD

OF ENTOMOLOGY AND MR

OF ......................

GEORGIA, RELATIVE TO THE GROWING OF IMPROVED WILT RESISTANT

COTTON AND COWPEA SEED.

Whereas, it has become necessary for the control of the destructive diseases, cot

ton and cowpea wilt and root knot, to provide a sufficient quantity of seed of varieties

resistant to these diseases to supply the increasing demand, and to insure the mainte-

nance and further improvement of such varieties; and

Whereas, the Bureau of Plant Industry United States Department of Agricultw'e

and the Georgia State Board of Entomology have entered into co-operatioR to encourage

private farmers to engage in the business of propagation and improvement of varieties

originated by the Department or Board of Entomology, the following agreement is entered

into between Mr

of

, Georgia,

and the Bureau of Plant Industry United States Department of Agriculture in co-opera

tion with the State Board of Entomology for the furtherance of the above mentioned

objects.

. On the part of the grower it is agreed to engage in the propagation of improved

::leed of.

wilt resistant cotton and

cowpeas for sale;

to improve the same annually by the progeny row and increase plot method of breeding;

to use all practical precautions in the matter of picking, ginning, prevention of other

disel'oses, etc., and to preserve the purity and wilt resistance of the seed under the super-

vision, and with the assistance of the representative of the above mentioned Department

and Board of Entomology, to offer such seed for sale at a reasonable price not exceed-

ing $1.50 per bushel for cotton and not over $3.50 for cowpeas, and to offer only such

seed of these varieties for sale for seeding purposes as have been grown by him (unless

otherwise definitely stated) and conform to the standards set by the Department of

Agriculture and the Board of Entomology.

The Bureau of Plant Industry or Georgia State Board of Entomology agrees to fur-

nish or make available for purchase by the grower, at $1.00 per bushel, 5 to 25 bushels

of select seed of Dixie (Dillon or Modella) variety of cotton for the planting of his seed

fields; to furnish information relative to methods of breeding, selection, etc.; to inspect

the crops and give the grower an official certificate of inspection at tbe end of the sea-

son, setting forth the eharacter of the seed produced.

Co-operative Seed Grower.

Joint Representative, United States Department of Agriculture and Georgia State Board- of Entomology.

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