This is the update version of the 1998 Primary Apple Scab Infection Periods for the Peach Ridge Weather Station in Sparta Michigan.
1998 Peach Ridge Data Version June 10, 1998 
Rain 
No.
Stage
McIntosh
Date
Start
Time
Rainfall
Hours
Ave.
Temp.
Fo
Mills
Severity
*Spores
/rod
Index
DDBase
32
% Mature
Spores
Predicted
Lesion 
Date
Date 
Lesion
Found
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1.
1st Green
3-30
 11:30 am
.02
3
67
None
3
Light
0
0
4-20
 
2.
1st Green
3-31
7:00 am
 1.22
 42
51
Heavy 
1923
Light
26
1
4-21
4-22
3.
1/4" Green
4-7
1:30 am
.39
30.5
42
Light
480
Light
117
3
4-24
4-25
4.
1/2" Green
4-13
7:00 pm
.86
80
46
Heavy
17600
Heavy
223
12
4-30
4-30
5.
Tight Cluster
4-21
Variable
 ?
?
50
None?
10500
Heavy
330
23
5-5
 5-5?
6.
Open Cluster
4-26
12:00 am
.62
16
45
Light
 1200
Light 
447
49
5-8
 5-9?
7.
Pink
4-29
8:00 am
.04
7
46
None
180
Light
495
62
5-9
 
8.
Pink
4-30
6:00 pm
.88
65
56
Heavy
186
Light
521
65
5-10
5-11?
9.
Full Bloom
5-6
11:30 am
.08
13
60
Moderate
900
Light
650
85
5-15
5-15?
10. 
9 DAFB 
5-13
2:00 am
.63
8
60
Light?
6
Light
918
100
5-23
 
11.
19 DAFB
5-23
11:00 pm
.04
14+
52
Light
177
Light
1289
 
6-5
 
12.
 24 DAFB
5-28
11:00 am
.03
14
62
Light
27 
Light 
1381
 
6-9
 
13.
 25 DAFB
5-29
1:30 am
.04
9
64
Light
2400
Light
1415
 
6-12
 
14.
 27 DAFB
5-31
5:30 am
.26
3
41
None
174
Light
1485 
 
6-14
 
15.
36 DAFB
6-9
 10:30 pm
.40
60
61
Heavy
0
 
1667
 
6-19
April 22 lesions found on the bottoms of leaves 1, 2, 3 and 4 in moderate numbers.
April 25 lesions found on the bottoms of leaves 3 and 4, and maybe 1 and 2 in light numbers.
April 30 lesions were found as sheet scab with heavy numbers on many leaves 1 to 6. Both tops and bottoms.
May 5 lesions were found on the tops and bottoms of early leaves in areas outside Peach Ridge.
May 11 and May 15 lesions were found on the tops and bottoms of leaves 6, 7 and 8, in light numbers.
Rain 5, 4-21, was quite variable and only a trace of rain fell at the Peach Ridge Weather Station.  Considerable rain fell at the scab monitoring station.
*Actual spore counts collected from a Peach Ridge commerical orchard that had scab last year. 
**Data based on B-E DD calculations.
Spores levels guide
Spore Maturity Guide
DD Base 32 Fo
% Mature Spores
Light
Moderate
Heavy
0-3000
3000-6000
6000+
320
445
565
736
750
765
800
830
880
25
50
75
95
96
97
98
99
100

.