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Rhode Island Apple
IPM
Mills Table -
Apple scab infection periods
Average
Temp. |
Hours of leaf wetness
Relative infection level
|
Days till first
lesions |
|
Low |
Moderate |
High |
|
| 78 |
10 |
14 |
23 |
|
| 77 |
8 |
11 |
18 |
|
| 76 |
6.5 |
9 |
16 |
|
| 61-75 |
6 |
9 |
16 |
9-10 |
| 60 |
6.5 |
10 |
17 |
11 |
| 57-59 |
7 |
11 |
19 |
12-13 |
| 55-56 |
8 |
12 |
20 |
13-14 |
| 54 |
8.5 |
13 |
21 |
14 |
| 52-53 |
9 |
14 |
22 |
15 |
| 51 |
10 |
15 |
24 |
16 |
| 50 |
11 |
16 |
26 |
16 |
| 49 |
11.5 |
17 |
27 |
17 |
| 48 |
12 |
17 |
27 |
17 |
| 47 |
14 |
20 |
32 |
17 |
| 46 |
16 (13) |
21 |
34 |
17 |
| 45 |
17(15) |
23 |
37 |
17 |
| 44 |
19 |
25 |
40 |
17 |
| 43 |
21(18) |
27 |
44 |
17 |
| 42 |
23 |
30 |
47 |
17
|
| 41 |
21 |
34 |
50 |
? |
| 40 |
29 |
38 |
53 |
? |
| 39 |
33(28) |
42 |
57 |
?
|
| 38 |
37 |
47 |
61 |
? |
| 37 |
41(30) |
52 |
65 |
? |
| 36 |
48(35) |
69 |
93 |
? |
| 34 |
48(41) |
69 |
93 |
? |
|
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Adapted from the table of W. D. Mills, revised by W. E.
MacHardy. Numbers in parenthses are the minimum hours of continuous leaf
wetness that resulted in scab lesions on apple leaves inoculated with
ascospores at controlled temperatures from 36 to 46 (reported by Gadoury
et al. in the New York Fruit Quarterly.)
Low identifies the minimum hours for infection. Moderate
and high identify the hours of leaf wetness required for noticeale
increases in scab lesions. The average temperature during wetness should
be based on hourly temperatures.
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