1	Managing Apple Diseases Bill Turechek
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3	Disease Management Cultural Practices Resistant varieties Inoculum reduction Targeting leaf litter Fungicides Timing your first application Timing additional applications Calendar based Forecasting Fungicide choices
4	Apple Scab Resistant Varieties Britegold Dayton Enterprise Freedom Gold Rush Jonafree Liberty
5	Standard Application Timings 1: Silver Tip 2: Green Tip - ½ in Green 3: Tight Cluster 4: Pink 5: Bloom 6: Petal Fall 7: 1^st Cover 8-11: 2^nd-5^th Cover
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7	Disease Management Cultural Practices Resistant varieties Inoculum reduction Targeting leaf litter Fungicides Timing your first application Squash mounts and the degree-day model give an estimate of disease pressure Timing additional applications Calendar based Forecasting Fungicide choices
8	Squash Mounts
9	Degree Day Model
10	Green Tip/Half-inch Green First application should be a contact fungicide such as Dithane, Penncozeb, Polyram, or Captan If fire blight is a problem a copper application is perhaps your best choice Half-inch green may be your last opportunity to apply copper w/out the risk of fruit russet
11	Disease Management Cultural Practices Resistant varieties Inoculum reduction Targeting leaf litter Fungicides Timing your first application Timing additional applications Calendar based Forecasting Fungicide choices
12	Modified Mill’s Table
13	Tight Cluster A contact (protectant) could be applied here A strobilurin or SI+protectant fungicide may be applied here if disease pressure is high Vangard claims 48 hr kickback activity Trials by Wilcox do support this claim SI+protectant has (at least) 48 hr kickback activity
14	Pink Typically, the peak period of apple scab activity Also a critical phenological stage for powdery mildew and rust diseases The 2 lb/100gal rate of mancozeb or captan will work well here as long as it is being applied as a protectant This spray will have little activity against PM SI+protectant or a strobilurin is a good choice if other diseases beside AS are of concern
15	Bloom If the period from pink to petal fall extends beyond fungicide protection, i.e., greater than 10 days, an application during bloom may be needed If an SI or strobilurin was used at pink, a contact fungicide may be a good choice here Keep in mind that the petal fall application may be less than 7 days away
16	Petal Fall In general, using an SI-mancozeb combination at tight cluster and pink followed by a strobilurin at petal fall and first cover is no better than reverse The SI+mancozeb combination will not be as effective as a strobilurin against black rot if used at petal fall and first cover A strobilurin at PF and first cover will provide excellent control of both black rot and fly speck Substituting captan for mancozeb could improve this mix against BR but would weaken it against FS
17	Petal Fall Where rusts are a concern, note that strobilurin’s have little activity against them SI+protectant should be used at tight cluster and pink to prevent fruit rust And between petal fall and 2nd cover to prevent terminal leaf rust infections
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19	Disease Management Cultural Practices Resistant varieties Inoculum reduction Targeting leaf litter Fungicides Timing your first application Timing additional applications Calendar based Forecasting Fungicide choices
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21	Dormant / Silver Tip Shredding leaf litter in November or April will reduce the risk of apple scab by 80-90% if all the leaf litter is shredded (Sutton et al., 2000) The risk of apple scab is reduced to 50-65% if 10-35% of the leaf litter can not be shredded because the offset of the flail mower Application of urea to the litter when 95% of the leaves have fallen will reduce the risk of scab 50% The risk is reduced to 66% if the application is made in April before budbreak
22	Powdery mildew life cycle
23	Powdery mildew life cycle
24	Powdery mildew life cycle
25	Powdery mildew life cycle
26	Powdery mildew life cycle
27	Powdery Mildew
28	Powdery Mildew
29	Powdery Mildew
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32	Why Is Fire Blight So Problematic? Unlike apple scab, the fire blight bacteria are dispersed several weeks prior to 1^st infection Erwinia amylovora (the FB bacterium) is a competent epiphyte The doubling time of the pathogen is about 20-30 minutes when temperatures are between 65-75 F…1 cell can turn into 1 trillion cells in just 2-3 days!!
33	"Infection can occur in minutes" Infection can occur in minutes, thus, almost any wetting event is a possible infection event New infections produce many new bacteria which are efficiently transmitted by insects, wind, and rain Trauma events put almost every orchard at risk
34	Practices That Increase FB Risk High density plantings The dwarfing rootstocks M-9 & M-26, which make high-density plantings possible, are highly susceptible to Fire Blight New fresh market varieties such as Gala, Fuji, Braeburn, etc. are very susceptible to fire blight
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36	Managing Fire Blight The Big 3 Horticultural practices designed to minimize orchard susceptibility and disease spread Inoculum reduction to reduce disease pressure Well-timed bactericide sprays to serve as a protective barrier from new infections
37	Horticultural Practices Avoid planting susceptible varieties on susceptible rootstocks (M.9, M.26) Susceptible varieties include: Gala Monroe Fuji Paula Red Crispin Rhode Island Greening Ida Red 20 Ounce Jonathan Rome Beauty
38	Horticultural Practices Pruning and fertilization practices should be done to minimize excessive shoot growth to manage shoot blight Blighted shoots should be pruned as soon as they are discovered Cuts should be made at least 8-12 inches below visible symptoms Sterilizing pruning shears is commonly recommended But in practice…it is often impractical or of limited value
39	Vector Control Manage insects with piercing and sucking mouth parts (e.g., aphids, leaf hoppers, and pear psylla) can be important in minimizing shoot blight
40	Inoculum Reduction Dormancy Prune cankered limbs and branches Green Tip Use of copper at or shortly after green tip will reduce bacteria produced in OW cankers Petal Fall Scout for infected shoots and prune immediately Pruning serves little value if done after numerous infections appear Prune regularly through the season as new cankers appear
41	Bactericides Apply streptomycin according to the MARYBLYT predictions Must be applied the day before or the day after a high risk or an infection event is predicted Thorough coverage is critical! Streptomycin must reach the stigmas where the bacteria multiply Streptomycin may be less effective if tank-mixed with chemicals (particularly foliar nutrients) containing calcium and/or phosphorus
42	Bactericides Serenade (B. subtilus) applied after streptomycin Useful in rotation RESISTANCE MANAGEMENT Messenger has NOT worked consistently Must be used in a protective mode Not very useful for BB Apogee is used to manage shoot blight NOT BB Down the road…. Phyton 27: a “safe” formulation of copper sulfate Oxolinic acid: a quinoline-family antibiotic Registered in Japan & Israel
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44	MARYBLYT: Introduction MB is a comprehensive computer program for predicting Fire Blight of apple and pear Use of MB has resulted in a marked improvement of FB and in a reduction in the number of antibiotic sprays applied
45	MARYBLYT: Introduction Developed by Paul Steiner and Gary Lightner, introduced in 1989, and has been used extensively by mid-Atlantic growers Identifies and predicts infection events and the appearance of symptoms for blossom blight, canker blight, shoot blight, and trauma blight Operated in real time to assess current FB risk or it can be run in simulation mode for predicting future events
46	MARYBLYT MARYBLYT integrates 3 cumulative heat unit “clocks” to indirectly monitor host (flowering), pathogen (epiphytic inoculum potential), and symptom development EIP: measures risk of infection by tallying cumulative degree hours above 65 F
47	Epiphytic Inoculum Potential (EIP)
48	MARYBLYT: Blossom Blight Flowers open w/ stigmas and petals intact EIP exceeds 100: 198 DH>65 F w/in the last 80 DD>40 F (apples) 198 DH>65 F w/in the last 120 DD>40F (Pears) Wetting event of: 0.01 inch of dew or Rain OR 0.1 inch of rain the previous day Average temperature greater than 60 F
49	MARYBLYT: Blossom Blight When all 4 conditions are met in the sequence given infection occurs The first symptoms appear with the accumulation of 103 DD>55 F In real time this interval can vary between 5 to 30 or more days The degree to which any of the thresholds exceed their minimums provides a subjective basis for estimating the severity of blossom blight infection
50	MARYBLYT: Blossom Blight Cool weather has a negative effect on EIP A 3-day cool period reduces EIP to 0; unless EIP had previously exceeded 200 After an antibiotic application, EIP is reset to zero MB assumes bacterial populations were reduced to marginal levels
51	MARYBLYT: Blossom Blight BHWT: Simple ‘+’ or ‘-’ signs to indicate: B= Open blossoms H= EIP>100 W= Wetting event T= Avg. daily temp>60F Risk of infection is shown as: Low, Medium, High, or Infection
52	Which threshold do I use?
53	Possible Action Thresholds
54	Recommendation For moderately susceptible varieties Spray only when all 4 parameters have exceeded their thresholds For very susceptible varieties Spray when all 4 parameters have been exceeded For young trees spray when risk is I or H For older, less susceptible trees spraying when the risk is ‘H’ is thought to be a conservative approach---hopefully future research will allow us to better interpret the true risk of FB under this scenario
55	MARYBLYT: Canker Blight In areas where FB is established, canker blight should be expected every year Begin scouting orchards for canker blight symptoms about 300 DD>55 F after green tip Pruning out cankers should help reduce the amount of shoot blight
56	MARYBLYT: Shoot Blight A local inoculum source is required Usually develop after 103 DD>55 F after BBS or CBS MB forecasts for shoot blight are limited to the first early symptoms However, MB assumes: Insect vectors are present Average temperature is 60 F or greater
57	MARYBLYT: Trauma Blight Associated with late frosts, hail or high winds that damage the foliage Occurs anytime after early bloom when EIP>100 Symptoms develop after 103 DD>55 F
58	Cougarblight Developed by Tim Smith, Washington State University Predicts the risk of blossom blight Does not predict the development of symptoms “Hands-on” model---Model calculations are done w/ paper & pencil w/ the aid of a few tables
59	Cougarblight Calculate the sum of degree hours during bloom using a lookup table 4 days prior to predicting wetting period Evaluate the history of fire blight in your area Evaluate susceptibility
60	Cougarblight (Degree Day Table)
61	Cougarblight (Risk prediction)
62	Cougarblight vs MARYBLYT Cougarblight uses a qualitative measurement of inoculum pressure to gauge risk MARYBLYT predicts not only BBS, but canker, shoot, & trauma blight (as well as symptoms!) MARYBLYT is computerized MARYBLYT comes w/ a price tag
63	General Management Principles (Summary) If possible, plant resistant varieties Prune out infected shoots, spurs, and limbs A complete coverage copper spray at green tip Thoroughly cover all trees in a block, not just the susceptible varieties Sensibly-timed streptomycin sprays during the blossoming period; this can be done using MARYBLYT or Cougarblight as there recommendation are highly correlated under NY conditions
64	Disease Information On-Line Resources Cornell Fruit Information page http://www.cornellfruit.com Tree Fruit and Berry Pathology Page NY IPM Program Printed Resources NRAES Production Guides Pest Management Guidelines for Tree Fruit Crops www.cce.cornell.edu/publications/catalog.html Phone: (607) 255-2080