Page 6 



BETTER FRUIT 



April 



KuT iToT-Arruis 



T»T- SCA» 



2278 

 25."3 % 



3567 

 39.56 ?t 



O-IO 3201 



1042 



800 



209 



SSSc 



45.72 



22.31 



e.sz 



Tar-Avt-ScAt 



22.52% 



Figure 1. Summary of results obtained in Block 1. These trees were sprayed 



foLir times, the ".30-day" spray being omitted 



m 



T0T AprLEslToT.5 eA>| /!^ScAslT0TAyI.ScAl 



2-171 



66.'42X= 



\^D-!0, 12 49 

 "Ft- I 3 3.5 7% 



44Z 



16.06 



12.41: 



20 1.6 



Figure 2. Summary of results obtained in Block 2. These trees were sprayed 



five times 



the two sections are very distinct. An 

 infection of 12.58 per cent occurred in 

 tlie tops of tfie trees in tliis block, while 

 the lower fruits possessed 4.03 per cent 

 scab. Total average infection in this 

 block was 7.42; where five sprays were 

 used (Block 3) it was 1.57 per cent. 

 The possibilities of using the four- 

 spray schedule will be briefly discussed 

 later in the article. 



Relation of Fruit Production to Scab 

 Infection 

 In connection with the percentages 

 determined in Block .\, it is interest- 

 ing to take into consideration the sig- 

 nificance of the relative bearing areas 

 of the trees as shown in Figure 1, and 

 their relation to scab infection as 

 found in different parts of the trees. 

 The average production of fruit in 

 these areas does not vary greatly. This 

 distribution was as follows: Ground 

 to ten feet, 35.29 per cent; from ten 

 to fifteen feet, 39.56 per cent; from 

 fifteen feet to the tops of the trees, 

 25.13 per cent. As would be expected, 

 owing to the fact that trees of this size 

 reach their greatest diameter between 

 ten and fifteen feet, a larger amount of 

 fruit would be found in this section of 

 the tree than elsewhere. The quality 



of the fruit produced in this section 

 is average of the entire tree. As a rule, 

 however, the larger, physically finer, 

 and more highly-colored apples are 

 produced well toward the tops of the 

 trees, while the lower fruits are usu- 

 ally smaller and subject to more in- 

 juries, especially those caused by the 

 brown aphis. In referring to the loca- 

 tion of the scab on the trees, it is found 

 that 35.29 per cent of the poorer quality 

 fruit is subjected to a scab infection 

 of but 6.5 per cent, while 25.13 per cent 

 of fine quality fruit in the upper por- 

 tions of the trees suffers an average 

 loss of 45.72 per cent, due to the attack 

 of scab alone. In the case of the for- 

 mer, ordinary thinning will remove all 

 of the scab with no loss; in the upper 

 part of the trees, with nearly half of 

 the fruit infected, the disfigured apples 

 cannot be eliminated witliout a heavy 

 loss. That the variations which have 

 been discussed are not local or con- 

 fined to the particular orchard from 

 which these notes were taken was 

 brought out while checking uj) some 

 twenty odd scab experiments carried 

 on in several orchards. 'I'his variation 

 was found to exist, though not so pro- 

 nounced in many cases, in every one 

 of them. 



Supposed Late Infections Explained 



This analysis of the relation of scab 

 infection to the location of fruit on 

 the trees solves a point with reference 

 to reported late summer infection. 

 During the past two seasons many 

 growers have reported to the writer 

 that apple scab was developing rapidly 

 during August. An examination of 

 these reported orchards, however, 

 failed to disclose any pronounced de- 

 velopment of new scab. Large heavily- 

 laden trees usually stand upright, hold- 

 ing their fruit throughout the spraying 

 season in about the same location in 

 which bloom occurred, until late July 

 or early August. The fruit on many 

 of the lop branches, as shown in the 

 accompanying figures, reaches an aver- 

 age height of twenty-four feet. During 

 late summer and early fall the great 

 weight of fruit on these heavily-laden 

 branches causes them to bend strongly 

 downward. By the middle of August 

 the position of fruit on many branches 

 of the trees is largely reversed; i. e., 

 that fruit which during the spraying 

 season was located in the tops can now 

 be found in many cases at a distance 

 of from four to eight feet from the 

 ground. This bending of the branches 

 in the latter stages is quite rapid. The 

 orchardist, however, in his weekly or 

 fortnightly inspection, fails to note the 

 changes that have taken place or to 

 realize that different apples are being 

 examined than those watched during 

 the early summer. Instead, the grovi'er 

 is alarmed to find, as indicated in 

 Figure 1, an apparent increase in the 

 percentage of scab from perhaps 6.5 

 I)er cent (that which he had been 

 watching earlier) to possibly 45.72 per 

 cent, the degree of average top infec- 

 tion found on the trees studied. To 

 the observer unfamiliar with the 

 growth and development of this fun- 

 gous disease, the phenomenon just de- 

 scribed would appear to be that of 

 new development of the disease on 

 the fruit. 



Scab Development During Late Summer 



Our observations this year indicate 

 that little scab developed on the apples 

 after the first of August. In a large 

 series of experiments apples were 

 kept under observation and examined 

 monlhly to determine the relative in- 

 crease of scab during the season. Dur- 

 ing late summer few changes in the 

 percentages were noted. On the leaves, 

 however, apple scab was more or less 

 active during most of the past summer. 

 In notes under date of August 30, the 

 following is quoted: "Leaves examined 

 for apple-scab infection indicate that 

 the fungus is still active, as it has been 

 throughout the summer. On trees 

 whose fruit is practically clean there 

 is present much leaf infection, espe- 

 cially on the vigorously growing ter- 

 minal leaves, which in many cases arc 

 literally peppered with olive-green, 

 Mycelium-covered areas. The infec- 

 tion seems to be more conspicuous on 

 trees infested with green aphis, whose 

 leaves have been kept damp with a 

 coating of honeydew. 



