THESIS THE THINMG OF FRUIT H.T, COTTON ■ 1914 ALBERT R. MANN LIBRARY New York State Colleges OF Agriculture and Home Economics AT Cornell University Cornell University Library SB 355.C85 The thinning of fruit- The original of this book is in the Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924002820847 THESIS. II THE THINKING OFFRUIT, BY R,t! COTTON. SB 327940 THIUNING OP FRUITS. The ©"bjectLof this thesis is to present in a ■con- cise form the results of the several experiments on the thinning of fruit that have been carried on in the various parts of the United States. Thinning of fruit has been practiced in Europe for many years but until lately .little has been done in the United States, Thinning consists in reducing the number of fruits^ on each tree to the extent that each individual fruit may be developed to the highest possible perfection without overtaxing the tree. No exact rule for thinning should be laid down, for the requirements vary with the different varieties of fruit and the different individual trees, and with the same tree in different seasons . The amount of thin- ning should be suited to the conditions as shown by the age and conditions of the tree, by the amount of fruit which has set and by the distribution of the fruit on the tree . In the consideration of the advisability and the profitability of thinning , there are more phases than one . The first one to be considered is the direct finan -cial returns, does thinning increase the total sel- ling price of the crop of fruit. In a good many cases it does, in some cases it does not. The following tables are an extract from work done by P. H. Ballou in Ohio, and they demonstrate the in- crease in selling price due to judicious thinning. Unthinned tree, dumber of apples set and r1^^q ^^|Hr^o>^ finftT TTo of Apples wt. iA Bushels % of grades Selling Price picked. lbs. ^ Firsts 2736 760 15.20 56.33 |I2. 93 Seconds 2629 478 9.b6 35.43 4.06 "Defectives 456 Under 2 in. 260 760 15.20 56.33 478 9.b6 35.43 83 1.66 8.22 28 .56 Total 116.98 Thinned tree, thinned to 8 in. apart. Nvimber set 7591. Thinned by 1750 Firsts 4067 1240 24.8 78.63 $21.08 Seconds 1280 256 5.12 16.23 I 2.17 Defectives350 70 1.4 5.13 Under 2 in. 72 II .22 123.25 This is rather an extreme case but it gives a good idea of the profit of thinning. The second phase to "be considered is that of main- taining the vigor of the trees, to maintain the natural vigor, overbearing must he avoided. If a tree is heav- ilyloaded and is allowed to remain so, the energies of the tree are spread over the larger number, and few if any will reach the limit of their possible growth. The capacity of a tree is limited and it cannot be exceeded, no matter how many fruit are set. It is not the size of the fruit but the number of seeds , which are allowed to mature, that impairs the vitality of the tree. In many cases where thinning is not resorted to the trees are broken down and often ruined, and in addition the next year|icrop is cut down owing to the fact that a heavy load will utilize the plant food that should be used for next years crop. In Missouri \¥. H. Chandler in work- ing with peaches found also that in every case a heavy crop of fruit tends to leave "fe&Siateave the buds in a con- dition to be more easily killed the following winter by the frost. Thus overbearing without thinning %• cause alternate cropping and this is not desirable. Although thinning will not entirely alter the alternate cropping habit of some of the longer established varieties of fruits it can be practiced on the newer varieties and an annual cropping habit be established. The natural tendency of some varieties of fruit seems to be to overbear, the Abundaxice Plum for example starts to bear even in the nursery row and if allowed to go unthinned dies at a very^age. It is a rule among ?:,nimal breeders that animals shall not be allowed to bear their young until a certain 8 :age of maturity is reached, and this should hold equally true for the fruit trees. Those varieties that have a tendency to bear heavily when young should be severly pruned for a few years and the amount of fruit gradually increased every year. The third phase is the effect on the fruit it- self, the difference betv/een thinned fruit and \in- thinned fruit is often very marked, in size, color, qualityand general attractiveness. In practically all the experiments that have been conducted, the size of the thinned fruit was increased materially. The extract below is a typical example of the result -s obtained. Tree Total no. Iio . Ists. 2nds barrels barrels F.o . in barrel of apples thinned of Ists of 2nds of Ists 6270 1450 3615 1205 6 2]/25 i 16/25 536 5605 check I7I0 3895 3 5 II/25 570 ro. in barrels value of fruit time used in thinning of 2nds 755 |9.80 2 1/3 hours 755 $7.62 This same table illustrates the fact the general quality of the thinned fruit is oetter, for there are 6 21/25 barrels of firsts of the thinned fruit to 3 barrels of firsts of the unthinned fruit. The small diseased and ill shaped fruit is eliminated by thin- ning, and the strength of the tree goes to mature the good fruit left. Thinning separates the fruit so that the sun can get into all of them, and the fewer number gives the tree a better chance to mature them earlier and these two factors insure a higher and more attractive color for the fruit. These factors greatly increase the mar -ket value of the fruit and where the fruit is put in attractive boxes, it is highly profitable to thin. The fourth phase is the control of disease . Proper thinning is a very important factor in the control of insect and fungus pes ts.G .H.Powell of Deleware in ex -periments with plums, estimated that the nianber of decayed fruit was reduced 50fo on the thinned trees. In the apple trees the bunching of the fruit together is particularly' favorable for the ravages of the cod- ling moth and the brown rot Monilia Pructiaenum. V/hen brown rot is working on green or ripening fruit the rot starts on the side that is most protected from the sun and wind or where there is moisture. The rot is spread Lu ijjuii'Ba.d by spores that are borne by the wind to places of lodgement in some crevice between fruits. Where there is a heavy crop the fruits are extremel^ close together and often five or six are touching each other .If the rot sets in it will spread through the whole tree; With the coddling moth much the same is true the larvae readily travels from one apple to the other where they are close together and great havoc'is done. It is estimated that $10,000,000 damage is done every year by the codling moth in the United States, so there is need of taking every precaution against it. Proper thinning separates the fruit so that there is no danger of the spread of disease by contact and the free circu- lation of the air and the better ventelation and drying of the fruit in the center of the trees eliminates to a great extent the danger of the starting of a fiingus disease . Lastly thinning makes easier the picking and sorting of the fruit and this gain alone it is estimated, is sufficient to pay for the cost of thinning. The fruits are separate and are hence are easily pic- ked ; if they are not thinned there are many bunches where the fruits are so close together that it is almost impos -sible to pick one without knocking off some of the others. It has been estimated that four times as many fruits are knocked off in picking unthinnned than in pick; ing thinned fruit. The thinned fruit is also mostly for the grade known as "Firsts" and hence is easily graded, but the un thinned fruit is very mixed with alot of 2nds and culls and decayed or diseased fruit and takes a cor- respondingly long time to sort. The general directions for the thinning of all fruits is somewhat as follows: First take off all the diseased and ill shaped fruit, then thin out until the fruits are sufficiently far apart for the tree to be able to bring them to the finest condition of maturity without unduly taxing the vitality of the tree. The distance between fruits of course will differ with the variety , and are considered separately in the fol -lowing pages. The time of thinning varies somewhat with the variety but in general, for most varieties, the best time is as soon as possible after the June drop^ as soon as it is reasonably possible to determine which of the fruits will remain on the tree. APPLES. The necessity of thinning is more marked with, the apple than with any other fruit, and some varieties need it much more than than the others, for example the Russian apple Telopsky has very short stems and grows in clusters of from 3 to 8 and crowd each other off. The table below shows the result of thinning for this variety. Tree Ists 2nds windfalls value gain I 2bu. l/2bu. Ibu. $1,32 #1.20 2. l/2bu. 3bu, .12 Cost of thinning .35 Total gain $ .85 In a block of a thousand trees the gain would be$850. In the thinning of apples the general concensus of opinion of all the experimenters is that as soon after the June drop as possible from the I6th,to the 30th. of June is thetime for the thinning to be done. Mid-stammer thinning has been tried but is not so beneficial as the earlier thinning as the longer the surplus fruit is left on the greater is the loss to the tree. Tninning is only- profitable when the tree is overloaded. If a tree is overloaded' on one side and has no fruit on the other it should be thinned Just the same as ever for each side of the tree is nourished by a seperate sets of roots and they cannot support more than a certain amount. After the June drop then all the diseased and ill- shaped fi'uit should be off, then the remainder should oe thinned to about 8 or 9 inches apart depending somewhat on the variety, the results of tue experiments with apples seem to show that the best results are obtained when the apples are thinned to these distances. The following tables will show the truth of this statement. Winesap trees thinned to 8 3/4 inches Col. 170 Treatment Ex.F Boxes Ex.CBoxes Stand. L^ox CullBoxes Cost of t. , ;ii at fpl.75 at !J^I.50 at |0.85 at |0.i75 thinning Thinned 5.34-$9.35 3.07£$4.6I 3.2-^272 I.II-|0.I9 #0.64 check 2.5^4.38 I-$I.50 9^7.65 5.08-|0.89 The total gain per tree is ;;'.1.85 When trees are 16 by 32 ft.;85 trees to the acre the gain is |I57.25 per acre. Baldwin trees. Cyvr«..«rr^^T^ <^M° Tree Total no. of no. Ists 2nds Barrels Barrels no. in barrel apples thinned of firsts of 2nds of Ists 1450 3615 1205 6 21/25 I 16/25 536 I7I0 3895 3 5 II/25 570 925 2825 II50 5 10/25 I 16/25 530 2190 1970 4 2 16/25 547 170. in barrel Value Time used in thinning, of 2nds. #9.80 2 1/3 hours 17.62 #8.00 I 1/2 » 2 6270 3 5605 4 4900 5 4160 2 725 3 755 4 710 5 750 $7.00 Ohio. Thinned to 8 inches. _ , ^ ^ Unthinned. Eo. of apples set and matured 6081. Grade lo.of apples wt.in Ko.of %ot grades Selling price Toicked lbs. bushels Ists. 2736 760 15.20 56.33 $12.92 2nds. 2629 478 9.56 35.43 | 4.06 defectives456 83 1.66 8.22 under 2 in260 28 .56 Total |I6S. Thinned to 8 in. No. set 7519 thinned by 1750. Ists 4067 1240 24.8 78.63 $21.08 2nds ' 1280 256 5.12 16.23 $ 2.17 defective.s350 70 1.4 ) 5.13 under2 in. 72 II .22 Total $23.25 gain for thinned $ 6.27 These results are typical and serve to show gain. when apples are thinned to 8 inches apart. Beach at Geneva experimented with thinning apples from 4 to 6 inches apart and those thinned to 6 inches apart gave the best results; whether he would have gotstillbetter results is a question. He found that some trees as the Greening were not affected very much by thinning and were naturally vigorous enough to mature all the fruit they bore. The Baldwin and the Hub^ bardston and others showed marked improvement hy thinning. The cost of thinning has been estimated anywhere from 22 l/2fi to 64/2" per tree, the difference being due to the price of labor available and to the size of the tree and crop. Apricots. Very little has been done with regard to thinning the apricot, but S. A. Beach working in California found that the best results were obtained when the fruits were thinned toa distance of two inches apart, and when the fruits were of the size of hazel nuts, the earlie. the better after you can determine what fruit will stick. One of the most practical ways , however, and the most economical when thinning is necessary, is to thin them by pruning. Grapes . The thinning of the grape is not practiced commerc- ially where the grape is grown in the field, but fancy grapes grown in the hot house are often thinned to good advantage, the directions for this type of thinning are as follows :- The future bunch may be readily seen in the tiny one which first forms after the petals fail, if it is ill- shaped, lop sided, squat or dumpy at the base cut it out at once, l3ut if the upper part iias two well balanced shoul- ders and it tapers down to a point keep it. To have a perfect bunch it should taper dovm to a poirt at the base, which should consist of one good berry, if there is more than one cut them out with a pair of grape scissors, leaving but one; then v/ork on up to the top of the bunch cut- ting out all the berries that spoil the symmetry of the bunch using a small forked twig to hold the bunchwhile trimming so as not to handle the fruit. Thinning must be done when the berries are about 1/8 inch in diameter, for at that stage it is easy to calculate the amount of space to leave between the berries. Enough berries should be left so that they pack a little and thereby insure a firm bunch. Bunches v/ith tightly squeezed berries and bunches with loose berries are equally bad. Peaches The peach is another fruit that it is very necessary to thin, it usually sets very heavy crops and S.n. Fulton in Iiichigan found that when the peach trees were left without thinning they v/ere oroken down from the weight of the fruit and the fruit was so small as to be almost unsalable. C.A.Keffer working in Tennesse with Alexander treesthin- ned to 4 inches, this he found was highly satisfactory and the distancewae easy to judge being about the width of one ' shand . IftQien the average number of fruits per thinned tree was 412, while for the un thinned tree 1228 was the number. The thinned averaged up 2 1/8 inches in diameter and 2 l/4 inches long , while the un thinned fruit only- measured 1 5/8 by I 7/8inches and was unsalable . C. P. Close in Delaware working with five year old Elberta trees found best results when he thinned to 8 inches apart. Landsten of Maryland recomends thinning to 6 or 8 inches apart. They all recognize that all varieties increase in size, some such as the Sneed almost doubling as a result of thin- ning, a.lso brighter color, better quality and flavor, more fancy and first class fruit, less culls and higher prices are obtained and the trees are in better condition for a crop the following year. The general directions for thinning the peach may be summed up as follows, as soon as possible after the June drop, and before the fruit is an inch long thin to about 6 to 8 inches apart. The cost of thinning for mature and good sized trees has been estimated at about 20 cents per tree. A more economical method of thinning the peach is to thin ■fay pruning in the winter. Pears . Many varieties of pears, of which the ^aeffer is one of the most important, have the v/eakness of overbearing and should be thinned. The best results seem to be obtai- ned by thinning to 6 inches, when the pears are about the size of a robin's egg and as soon as possible after the June drop. The diseased fruit is first picked and then the remainder is thinned. The cost for 8 year old trees v/as estimated at 5 cents each. The cost would naturally increase v/ith the size of the tree and would be influenced by the labor available. Plums . Among the plijms thinning has different effects. The Lombard and Japanese varieties respond quickly to thinning, the result being a large increase in size and quality, while the Damson type does not show any marked difference in size or quality betv,reenthe thinned and the unthinned fruit, sev- eral varieties have the tendency to bear when very young, the Abundance for instance bears while in the nursery row and in consequence is short lived. Plum varieties with this habit should be thinned very severlj/ at first and the amount of fruit gradually increased each year. Thinning reduces the amount of decayed fruit to a consed- erable extent .G.H.Powell of Deleware working with 10 year old Bur'ba.nk plums found that oy thinning the numlDer of decay -ed fruit was reduced: 50^. Thinned to Ho . of decayed plums >of decayed plums 4 inches I 2 3 44 39 35 II. 4 12.4 10.5 8 inches I 2 3 26 21 29 13.8 5.6 8.9 Check I 2 109 304 209 109 27.5 29.4 20.5 P.Garcia of New Mexico had some very striking results in thinning Clyman, Wild Goose, Tragedy and Yellow Egg plums, the following tables illustrate the value of thinning as he found it. Name distance ??^Istclass ^of 2nd classfruit /^of 3rd. class fruit thinned fruit Wild Goosel 6 in. 75.7 24.2 2 3 in. 70.1 28.8 3 none 67.4 32.5 I 6 in. 93.4 6.5 Clyman 2.3 in. 3. none 85.9 53.7 14 46.2 1,6 in. 86.4 13.5 Tragedy 2.3 in. 3 .none 96.9 53.7 3 46.2 1.6 in. 81. 1 15.9 Yellow Egg2.3 in. 3. none 57.5 27.5 30.6 53 2.8 II .8 19.3 The second class was unsalaole commercially so it can be readily seen that tine thinned fruit has a tremendous adv- antage over the unthinned fruit. The general directions for thinning are as follows. When the plxoms are of the size of a pigeons egg take off all the diseased fruit, and then thin to from 3 to 6 inches apart, depending upon the variety. The cost of thinning 10 year old trees was estimated at 10 cents per tree, the cost will vary with the size of the tree. List Of References. Colorado Bull. II8& 139 by Whipple. Colorado Bull. 170 by R.S.Herrick. Connecticut Storrs Rpt. 190 by E.R.Bennet. Delaware Rpt. 1900 By G.H.Powell. Delaware Rpt. 1902 by C. P. Close. Delaware Rpt. 1899 by G.H.Powell. Maryland Bull, No. 82. Maryland state Horticultural Soc. 5,1902. jlass. Hatch Bull,. 44 By S.T.Maynard, J. H. Putnam, and S.W. Fletcher. Michigan Bull. 187 and special bull. 27 by S.H.Fulton, and T.A.Farrand. l-^issouri Research Bull. 8 & 74 by V/.H. Chandler. Montana Rpt. 1905-6 by R. "W.Fisher. Few r.exico Bull. 39 by F.Garcia. >Tew JerseyRpt. 1900 bjy T.Jordan. New York State Bull. 39 by S. A. Beach. Tennesee Bull. 88 Ohio Bull 240.