Friday, June 23, 2017

Extended wetting event June 16-17, and accumulated wetting hours


The past 10 days there was one extended wetting at our AREC event that could contribute to summer disease pressures in the coming weeks: Jun 16-17, wet 20 hr at 70° with 0.62 in. rain. 

For purposes of predicting the development of the sooty blotch and flyspeck (SBFS) fungal complex, we record accumulated wetting hours from rainfall or dew, starting 10 days after petal fall. This year our petal fall date at Winchester was Apr 24, so the start of wetting hour accumulation was from May 4. As of Friday morning June 23, accumulated wetting hours (ACW) toward the 250 wetting hour threshold for specific treatment against the SBFS fungal complex were: at 909 ft elevation, 316 hr (with the 250-hr threshold reached Jun 7); at 932 ft (the AREC NEWA station), 226 hr; and at the 983 ft elevation, 183 hr ACW.  Reaching of the 250 hr threshold predicts that the fungi causing SBFS symptoms are now present on unprotected fruit and that symptoms on such fruit should appear in about 2 weeks.

For Nelson County in central Virginia, the petal fall date was Apr 20, and accumulation of wetting hours from Apr 30 is recorded by weather stations at different elevations at Tyro. Wetting hour accumulation in central Virginia was slow last week. As of June 23, a sensor placed at 1465 ft. elevation had accumulated only 90 wetting hours from Apr 30, while the one placed at 941 ft elevation had accumulated 341 hr- just over the 250-hr threshold).

The NEWA station at Gadino Cellars (elev. 665 ft, in Washington, VA) passed the threshold of 250 ACW last week, and has now recorded 286 wetting hours since May 1. A NEWA station at Fishersville has also passed the 250-hr threshold with 294 ACW.

Tuesday, June 13, 2017

Accumulated wetting thresholds reached at lower elevations


The past week there have been a minimal amounts of rainfall in the Winchester and central Virginia areas, but there continues to be wetting hour accumulation at the lower elevations. 

For purposes of predicting the development of the sooty blotch and flyspeck (SBFS) fungal complex, we record accumulated wetting hours from rainfall or dew, starting 10 days after petal fall. This year our petal fall date at Winchester was Apr 24, so the start of wetting hour accumulation was from May 4. As of Monday morning June 12, accumulated wetting hours (ACW) toward the 250 wetting hour threshold for specific treatment against the SBFS fungal complex were: at 909 ft elevation, 271 hr (21 CWH over the 250-hr threshold); at 932 ft (the AREC NEWA station), 184 hr; and at the 983 ft elevation, 153 hr ACW. In the past week most of the wetting hour accumulation was from dew and occurred more at lower elevations in the orchard. Note that at the lowest elevation, the ACW of 271 hr reached the threshold level of 250 ACW on June 7. This predicts that the fungi causing SBFS symptoms are now present on unprotected fruit and that symptoms on such fruit should appear in about 2-3 weeks.

For Nelson County in central Virginia, the petal fall date was Apr 20, and accumulation of wetting hours from Apr 30 is recorded by three weather stations at different elevations at Tyro. Wetting hour accumulation in central Virginia was slow last week. As of June 5, a sensor placed at 1465 ft. elevation had accumulated only 76 wetting hours from Apr 30, while the one at 1165 ft. had accumulated 164 wetting hours, and the one placed at 941 ft elevation had accumulated 254 hr- just over the 250-hr threshold).

The NEWA station at Gadino Cellars (elev. 665 ft, in Washington, VA) is approaching the threshold level of 250 ACW this week, having recorded 246 wetting hours since May 1. A NEWA station at Fishersville is also approaching the 250-hr threshold with 238 ACW.

Tuesday, June 6, 2017

Early summer disease activity


For purposes of predicting the development of the sooty blotch and flyspeck (SBFS) fungal complex, we record accumulated wetting hours from rainfall or dew, starting 10 days after petal fall. This year our petal fall date at Winchester was Apr 24, so the start of wetting hour accumulation was from May 4. As of Monday morning June 5, accumulated wetting hours (ACW) toward the 250 wetting hour threshold for specific treatment against the SBFS fungal complex were: at 909 ft elevation, 241 hr; at 932 ft (the AREC NEWA station), 180 hr; and at the 983 ft elevation, 143 hr ACW. In the past week most of the wetting hour accumulation was from dew and occurred more at lower elevations in the orchard. Note that at the lowest elevation, the ACW of 241 hr will probably reach the threshold level of 250 ACW this week.

For Nelson County in central Virginia the petal fall date was Apr 20, and accumulation of wetting hours from Apr 30 is recorded by three weather stations at different elevations at Tyro. Wetting hour accumulation in central Virginia was slow last week. As of June 5, a sensor placed at 1465 ft. elevation had accumulated only 76 wetting hours from Apr 30, while the one at 1165 ft. had accumulated 151 wetting hours, and the one placed at 941 ft elevation had accumulated 199 hr.

The NEWA station at Gadino Cellars (elev. 665 ft, in Washington, VA) will probably also reach the threshold level of 250 ACW this week, having recorded 238 wetting hours since May 1.

We have had several reports of other early summer disease activity: bitter rot mummies forming on fire-blighted shoots and early Glomerella leaf spot symptoms in central Virginia and Alternaria leaf blotch on Red Delicious in Rockingham County.

Wednesday, May 31, 2017

Disease Update; Accumulated wetting hours and extended wetting events


Early this week we recorded another extended wetting event at our AREC: May 28-29, wet 12 hr at 63° with 0.04 in. rain. 

For purposes of predicting the development of the sooty blotch and flyspeck (SBFS) fungal complex, we record accumulated wetting hours from rainfall or dew, starting 10 days after petal fall. This year we chose Apr 24 as our petal fall date for Winchester, so the start of wetting hour accumulation was from May 4. As of Monday morning May 29, accumulated wetting hours (ACW) toward the 250 wetting hour threshold for specific treatment against the SBFS fungal complex were: at 909 ft elevation, 204 hr; at 932 ft (the AREC NEWA station), 167 hr; and at the 983 ft elevation, 139 hr ACW. In the past week some wetting hour accumulation occurred from both rainfall and dew. 

For central Virginia, we have selected Apr 20 as the petal fall date, and accumulation of wetting hours from Apr 30 is recorded by three weather stations at different elevations at Tyro. As of May 29, a sensor placed at 1465 ft. elevation had accumulated only 75 wetting hours from Apr 30, while the one at 1165 ft. had accumulated 147 wetting hours, and the one placed at 941 ft elevation had accumulated 187 hr.

The NEWA station at Gadino Cellars (elev. 665 ft, in Washington, VA) has recorded 206 wetting hours since May 1.

Friday, May 26, 2017

More of the same...


We have had several more extended wetting periods this week, favorable for both scab and cedar-apple rust and early summer disease development: May 23-24, wet 11 hr at 54° with 0.48 in. rain; May 24-25, wet 15 hr at 55° with 0.96 in. rain; . May 25-26 wet more than 9 hr at 56° with 0.56 in. rain.

Apple scab pressure has been significant this year, with five infection periods Mar 27- Apr 7 and enough rainfall to cause weathering of protectant fungicides during that time. Lesions from those infection periods were present to cause secondary infection Apr 22-26 and during later infection periods May 4-6, May 11-13, May 21-22, and the recent ones this week. Combinations of fungicides with protective action and after-infection activity for scab are suggested for control during repeated conditions with 1-2 inches of rainfall followed by extended wetting that favors additional infection.

Cedar-apple rust: Rusts have been active for 8 weeks and cedar rust galls were still active May 25-26. Cedar-apple rust lesions and some quince rust lesions are present from the Apr 24-26 and May 4-6 infection periods and more foliar infection is appearing from the more recent ones. Considering continued cedar gall activity and infection conditions this week, it would still be prudent to include an SI fungicide for after-infection rust control in the next application if there is any doubt about lack of protective residue. The recent wetting will add to the accumulated wetting hour totals for development of sooty blotch and flyspeck which will be updated early next week.

Stone fruits: Continue to protect peaches against peach scab which is also favored by the above conditions described for apple scab. Also, protect ripening cherries against brown rot and Alternaria rot which are favored by these wet conditions during the pre-ripening period.

Tuesday, May 23, 2017

Disease update May 23.


We have some continuing apple scab activity, with a secondary infection period across the region from Winchester southward to Roanoke and east of the Blue Ridge May 21-22. Length of wetting varied from 7-16 hr at temperatures of 58-70° and mostly less than an inch of rain. More extended wetting is forecast for May 23-24. Later this week and early next week we expect secondary scab lesions to appear from the heavy secondary infection period May 11-13 

For purposes of predicting the development of the sooty blotch and flyspeck (SBFS) fungal complex, we record accumulated wetting hours from rainfall or dew, starting 10 days after petal fall. This year we chose Apr 24 as our petal fall date for Winchester, so the start of wetting hour accumulation was from May 4. As of May 22, accumulated wetting hours (ACW) toward the 250 wetting hour threshold for specific treatment against the SBFS fungal complex were: at 909 ft elevation, 127 hr; at 932 ft (the AREC NEWA station), 109 hr; and at the 983 ft elevation, 84 hr ACW. In the past week some wetting hour accumulation occurred from both rainfall and dew. 

For central Virginia, we have selected Apr 20 as the petal fall date, and accumulation of wetting hours from Apr 30 is recorded by three weather stations at different elevations at Tyro. As of May 22, a sensor placed at 1465 ft. elevation had accumulated only 35 wetting hours from Apr 30, while the one at 1165 ft. had accumulated 83 wetting hours, and the one placed at 941 ft elevation had accumulated 115 hr.

Apple powdery mildew remains active on susceptible new growth. Mildew is a dry weather disease, and conidiospores were available for infection at Winchester as early as Mar 27. Since then we have had 23 days suitable for mildew infection through May 22. 

East of the Blue Ridge we have seen several examples of fire blight blossom infection.

Monday, May 15, 2017

Apple scab infection period May 11-13. Early summer disease developments.


At Winchester we recorded a heavy secondary apple scab infection period May 11-13, with 46 hr wetting with a mean temperature of 49° and 1.82 inches of rain. This volume of rainfall could have eliminated much of the protective fungicide residue during the extended wetting to allow some scab and rust infection. 

Areas in the Valley, southward to Roanoke, and areas east of the Blue Ridge from Fauquier County south to Lynchburg and Danville also saw extended wetting periods ranging from 32-48 hr, all at temperatures in the low to mid-50s. The more southern areas had split wetting periods or two separate ones starting May 9. These conditions also favored peach scab infection.

Rusts have been active in the Winchester area for six weeks, and some cedar rust galls are still active. Cedar-apple rust lesions (shown below) and some quince rust lesions are now appearing from the Apr 24-26 infection period; others from the extended wetting May 4-6 are expected this week.


May 10, 2017. Early appearance of cedar-apple rust lesions and scab (upper left) from the infection period Apr 24-26.
Apple powdery mildew conidia were available for infection at Winchester as early as Mar 27, and there have been 18 “dry weather“ mildew days suitable for mildew infection from Mar 27 to May 14. The image below illustrates the appearance of a primary mildew shoot and secondary infection on an adjacent shoot. 

Adjacent Golden Delicious shoots infected with primary infection (right) and secondary infection (left). Primary infection emerges with shoot growth from an infected overwintering bud. Secondary infection is usually heavier near a primary inoculum source.

For purposes of predicting the development of the sooty blotch and flyspeck (SBFS) fungal complex, we record accumulated wetting hours from rainfall or dew, starting 10 days after petal fall. This year we have chosen Apr 24 as our petal fall date for Winchester, so the start of wetting hour accumulation is from May 4. As of May 14, accumulated wetting hours (ACW) toward the 250 wetting hour threshold for specific treatment against the SBFS fungal complex were: at 909 ft elevation, 98 hr; at 932 ft (the AREC NEWA station), 83 hr; and at the 983 ft elevation, 73 hr ACW. One of the purposes of following three weather stations is to compare wetting hour accumulation at different elevations; however, because many of the early wetting hours this year were a result of rainfall rather than dew, the early accumulation trend this year is a bit different than in some previous years. 


For central Virginia, we have selected Apr 20 as the petal fall date for accumulation of wetting hours by weather stations at Tyro. As of May 14, a sensor placed at 1465 ft. elevation had accumulated only 31 wetting hours from Apr 30, while the one at 1165 ft. had accumulated 72 wetting hours, and the one placed at 941 ft elevation had accumulated 94 hr.

Monday, May 8, 2017

Widespread scab and rust infection period May 4-6


WIDESPREAD SCAB and RUST INFECTION PERIOD: A widespread secondary scab infection period occurred May 4-6 from Danville, Roanoke and Lynchburg areas northward through Winchester. In Winchester we recorded 22 hr wetting with a mean temperature of
55° and 2.6 inches of rainfall. This volume of rainfall could have eliminated much of the fungicide residue early enough during the extended wetting to allow some scab and rust infection.

A survey of eleven NEWA weather stations in Virginia showed volumes of rainfall ranging around 2 to 3 inches at most recording stations, but Danville had 1.2 in. of rain and 18 hr wetting while some Albemarle County stations had more than 3 inches, and Rappahannock County had as much as 5.4 inches and 44 hr wetting. Temperatures were warm enough at all locations to allow cedar-apple rust infection wherever inoculum is still present. There are still active cedar rust galls at Winchester.

Also, these conditions May 4-6 favored peach scab infection.

FIREBLIGHT UPDATE: Fire blight conditions developed much as predicted in the May 1 post, with possible infection conditions May 1, only wetting lacking May 2, then declining risk with cooler temperatures that are predicted to continue through May 13. The remaining susceptible bloom in the Winchester area is mostly on recently planted trees. 

Monday, May 1, 2017

Fire blight outlook May 1-5.


NOTE: This year for fire blight risk assessment, we are comparing graphics from Maryblyt 7 and from the Cougarblight model as shown on our NEWA site. We are using the same weather data from our NEWA station to make these comparisons in both predictive programs.

CAUTION: The observations, conditions, and recommendations reported for Winchester, VA are provided as a guide to fire blight risk assessment only for the immediate area of the Virginia Tech AREC located six miles southwest of Winchester. Use of the information reported here for making orchard management decisions outside of that area is not our intent. Fruit producers outside of that area are encouraged to consult their state extension specialists for information similar to that provided here.
Maryblyt graphic May 1, 2017. Click to enlarge.
FIRE BLIGHT: Above is a cropped graphic from the Maryblyt 7 program, using Apr 5 as the date for first bloom open on Idared cultivar. Some early cultivars still have scattered susceptible bloom, while later cultivars are beyond petal fall but still with susceptible bloom in the Winchester and central Virginia areas. Some recently planted trees still have much susceptible bloom. The temperature and rainfall data are current through Sunday evening, Apr 30. Predicted weather conditions are shown for May 1-5. The components of fire blight risk are indicated in the columns labeled B (blossoms open), H (degree hours for epiphytic bacterial populations), W (wetting by rain or dew), and T (average daily temperature 60 F or above). For infection to be predicted, wetting must occur after the EIP (epiphytic infection potential) reaches 100 or higher. Based on recorded temperatures and wetting, the risk column shows high risk and possible infection with any wetting Apr 11-12, 15-18, 21 and, and if bloom persists, Apr 27-May 2. Infection was indicated for Apr 12, 15-17 21 and Apr 28-30. Predicted warming temperatures have again increased risk wherever susceptible bloom remains through May 2, then declines with cooler temperatures through May 5. Note that risk can change quickly with warmer than predicted temperatures and wetting. Continue to protect late bloom and open bloom on recently planted trees as needed.

The BBS column is tracking predicted symptom development for the first infection Apr 12 and symptoms are predicted to appear Apr 27. Later infections are tracked with letters b-e, and symptoms for those are predicted to appear Apr 28-May 2. The CBS column indicates progression toward the appearance of canker margin symptoms due to extension of overwintering cankers from last year, which were predicted to Apr 22. Canker advancement cannot be prevented by chemical treatment at this time and the presence of symptoms will signal build-up of inoculum which could become a factor in the event of a trauma blight/shoot blight situation due to hail injury, etc. To offset the potential for shoot tip infection in an active fire blight year such as this one, apply the plant growth regulator, prohexadione-calcium (Apogee, Kudos), at late bloom. Shoot blight suppression results from hardening off of vegetative shoot growth starting about 10 days after the initial application.

Below is the graphic from the Cougarblight model as shown on our NEWA site. Note that we selected orchard blight history option as “Fire blight occurred in your neighborhood last year” and first blossom open date as 4/5/2017. (This date must be re-set each time this site is accessed). Cougarblight shows color-coded risk as “extreme” Apr 28-May 3.
Cougarblight graphic May 1, 2017. Click to enlarge.

Friday, April 28, 2017

Fire blight outlook April 28-May 3.


NOTE: This year for fire blight risk assessment, we are comparing graphics from Maryblyt 7 and from the Cougarblight model as shown on our NEWA site. We are using the same weather data from our NEWA station to make these comparisons in both predictive programs.

CAUTION: The observations, conditions, and recommendations reported for Winchester, VA are provided as a guide to fire blight risk assessment only for the immediate area of the Virginia Tech AREC located six miles southwest of Winchester. Use of the information reported here for making orchard management decisions outside of that area is not our intent. Fruit producers outside of that area are encouraged to consult their state extension specialists for information similar to that provided here.
Maryblyt graphic April 28, 2017
FIRE BLIGHT: Above is a cropped graphic from the Maryblyt 7 program, using Apr 5 as the date for first bloom open on Idared cultivar. Early-blooming cultivars still have scattered susceptible bloom, and later cultivars are at petal fall but with much susceptible bloom in the Winchester and central Virginia areas. Some recently planted trees still have much susceptible bloom. The temperature and rainfall data are current through Thursday evening, Apr 27. Predicted weather conditions are shown for April 28-May 3. The components of fire blight risk are indicated in the columns labeled B (blossoms open), H (degree hours for epiphytic bacterial populations), W (wetting by rain or dew), and T (average daily temperature 60 F or above). For infection to be predicted, wetting must occur after the EIP (epiphytic infection potential) reaches 100 or higher. Based on recorded temperatures and wetting, the risk column shows high risk and possible infection with any wetting Apr 11-12, 15-18, 21 and, and if bloom persists, Apr 27-May 3. Infection was indicated for Apr 12, 15-17 and 21. Predicted warming temperatures have again increase risk wherever susceptible bloom remains Apr 26-May 1. Note that risk can change quickly with warmer than predicted temperatures and wetting. In situations where all other requirements for infection have been met except wetting (as for May 1-3, wetting from any spray application (fungicide, insecticide, or thinning spray) can provide the wetting trigger for infection to occur. In high-risk situations, a protective streptomycin application is recommended ahead of predicted infection. Continue to protect late bloom and open bloom on recently planted trees as needed.

The BBS column is tracking predicted symptom development for the first infection Apr 12 and symptoms are predicted to appear Apr 27. Later infections are tracked with letters b-e, and symptoms for those are predicted to appear Apr 28-May 2. The CBS column indicates progression toward the appearance of canker margin symptoms due to extension of overwintering cankers from last year, which were predicted to Apr 22. Canker advancement cannot be prevented by chemical treatment at this time and the presence of symptoms will signal build-up of inoculum which could become a factor in the event of a trauma blight/shoot blight situation due to hail injury, etc. To offset the potential for shoot tip infection in an active fire blight year such as this one, apply the plant growth regulator, prohexadione-calcium (Apogee, Kudos), at late bloom. Shoot blight suppression results from hardening off of vegetative shoot growth starting about 10 days after the initial application. The fire blight outlook will be updated Monday, May 1.

Below is the graphic from the Cougarblight model as shown on our NEWA site. Note that we selected orchard blight history option as “Fire blight occurred in your neighborhood last year” and first blossom open date as 4/5/2017. (This date must be re-set each time this site is accessed). Cougarblight shows color-coded risk as “high” for Apr 27 and “extreme” Apr 28-May 2. 
Cougarblight graphic April 28, 2017.

Wednesday, April 26, 2017

Heavy scab and rust infection period and fire blight outlook Apr 26-May 1.


NOTE: This year for fire blight risk assessment, we are comparing graphics from Maryblyt 7 and from the Cougarblight model as shown on our NEWA site. We are using the same weather data from our NEWA station to make these comparisons in both predictive programs.

CAUTION: The observations, conditions, and recommendations reported for Winchester, VA are provided as a guide to fire blight risk assessment only for the immediate area of the Virginia Tech AREC located six miles southwest of Winchester. Use of the information reported here for making orchard management decisions outside of that area is not our intent. Fruit producers outside of that area are encouraged to consult their state extension specialists for information similar to that provided here.

SCAB and RUSTS:  We have just seen extended wetting of more than 46 hours. Because apple scab lesions resulting from infection periods during the period March 26 to Apr 7 may have been present, consider this to be a heavy secondary infection period. Also, because of the high susceptibility of developing fruits to quince rust, it is suggested that fungicides with strong after-infection activity against rusts and scab be included in the next fungicide application.
Maryblyt graphic for Winchester, Apr 26, 2017. Click to enlarge.
FIRE BLIGHT: Above is a cropped graphic from the Maryblyt 7 program, using Apr 5 as the date for first bloom open on Idared cultivar. Early-blooming cultivars still have scattered susceptible bloom, and later cultivars are at petal fall but with much susceptible bloom in the Winchester and central Virginia areas. Some recently planted trees still have much susceptible bloom. The temperature and rainfall data are current through Tuesday evening, Apr 25. Predicted weather conditions are shown for April 26-May 1. The components of fire blight risk are indicated in the columns labeled B (blossoms open), H (degree hours for epiphytic bacterial populations), W (wetting by rain or dew), and T (average daily temperature 60 F or above). For infection to be predicted, wetting must occur after the EIP (epiphytic infection potential) reaches 100 or higher. Based on recorded temperatures and wetting, the risk column shows high risk and possible infection with any wetting Apr 11-12, 15-18, and 21, and if bloom persists, Apr 27-May 1. Infection was indicated for Apr 12, 15-17 and 21. Predicted warming temperatures will again increase risk wherever susceptible bloom remains Apr 26-May 1. Note that risk can change quickly with warmer than predicted temperatures and wetting. In situations where all other requirements for infection have been met except wetting (as for Apr 27-May 1), wetting from any spray application (fungicide, insecticide, or thinning spray) can provide the wetting trigger for infection to occur. In high-risk situations, a protective streptomycin application is recommended ahead of predicted infection. Continue to protect late bloom and open bloom on recently planted trees as needed.

The BBS column is tracking predicted symptom development for the first infection Apr 12 and symptoms are predicted to appear Apr 27. Later infections are tracked with letters b-d, and symptoms for those are predicted to appear Apr 28-30. The CBS column indicates progression toward the appearance of canker margin symptoms due to extension of overwintering cankers from last year, which would be predicted to occur after that value reached 100 Apr 22. Canker advancement cannot be prevented by chemical treatment at this time and the presence of symptoms will signal build-up of inoculum which could become a factor in the event of a trauma blight/shoot blight situation due to hail injury, etc. To offset the potential for shoot tip infection in an active fire blight year such as this one, apply the plant growth regulator, prohexadione-calcium (Apogee, Kudos), at late bloom. Shoot blight suppression results from hardening off of vegetative shoot growth starting about 10 days after the initial application. The fire blight outlook will be updated Friday, Apr 28.

Below is the graphic from the Cougarblight model as shown on our NEWA site. Note that we selected orchard blight history option as “Fire blight occurred in your neighborhood last year” and first blossom open date as 4/5/2017. (This date must be re-set each time this site is accessed). Cougarblight shows color-coded risk as “high” for Apr 27 and “extreme” for Apr 28-30. 
Cougarblight graphic for Winchester, Apr 26, 2017. Click to enlarge.

Monday, April 24, 2017

Fire blight and scab outlook April 24-28.


NOTE: This year for fire blight risk assessment, we are comparing graphics from Maryblyt 7 and from the Cougarblight model as shown on our NEWA site. We are using the same weather data from our NEWA station to make these comparisons in both predictive programs.

CAUTION: The observations, conditions, and recommendations reported for Winchester, VA are provided as a guide to fire blight risk assessment only for the immediate area of the Virginia Tech AREC located six miles southwest of Winchester. Use of the information reported here for making orchard management decisions outside of that area is not our intent. Fruit producers outside of that area are encouraged to consult their state extension specialists for information similar to that provided here.

APPLE SCAB lesions resulting from infection periods during the period March 26 to Apr 7 may be present in poorly protected orchards, and extended wetting could result in heavy secondary infection this week, Apr 24-26.

Maryblyt graphic for Winchester, Apr 24, 2017. Click to enlarge.
FIRE BLIGHT: Above is a cropped graphic from the Maryblyt 7 program, using Apr 5 as the date for first bloom open on Idared cultivar. Many trees still have some susceptible bloom in the Winchester area. The temperature and rainfall data are current through Sunday evening, Apr 23. Predicted weather conditions are shown for April 24-28. The components of fire blight risk are indicated in the columns labeled B (blossoms open), H (degree hours for epiphytic bacterial populations), W (wetting by rain or dew), and T (average daily temperature 60 F or above). For infection to be predicted, wetting must occur after the EIP (epiphytic infection potential) reaches 100 or higher. Based on recorded temperatures and wetting, the risk column shows high risk and possible infection with any wetting Apr 11-12, 15-18, and 21, and if bloom persists, Apr 27-28. Infection was indicated for Apr 12, and 15-17 and is predicted with wetting Apr 21. Note that risk can change quickly with unpredicted warmer temperatures and wetting. In high-risk situations, a protective streptomycin application is recommended ahead of predicted infection. Predicted cooler temperatures should reduce risk Apr 24-25, but will probably cause late bloom to persist, setting up higher risk of infection of late bloom with warmer temperatures Apr 27-28. Continue to protect late bloom and open bloom on young trees as needed.

The BBS column is tracking predicted symptom development for the first infection Apr 12 and symptoms are predicted to appear Apr 27. The CBS column indicates progression toward the appearance of canker margin symptoms due to extension of overwintering cankers from last year, which would be predicted to occur after that value reached 100 Apr 22. Canker advancement cannot be prevented by chemical treatment at this time and the presence of symptoms will signal build-up of inoculum which could become a factor in the event of a trauma blight/shoot blight situation due to hail injury, etc. To offset the potential for shoot tip infection in an active fire blight year such as this one, apply the plant growth regulator, prohexadione-calcium (Apogee, Kudos), at late bloom. Shoot blight suppression results from hardening off of vegetative shoot growth starting about 10 days after the initial application. The fire blight outlook will be updated Wednesday, Apr 26.

Below is the graphic from the Cougarblight model as shown on our NEWA site. Note that we selected orchard blight history option as “Fire blight occurred in your neighborhood last year” and first blossom open date as 4/5/2017. (This date must be re-set each time this site is accessed). Cougarblight shows color-coded risk as “extreme” Apr 21, and “high” Apr 22-23 then declining Apr 24-26, but returning to high and extreme Apr 27-28. 

Cougarblight graphic for Winchester, Apr 24, 2017. Click to enlarge.

Friday, April 21, 2017

Fire blight risk outlook for Winchester April 21-26.


NOTE: This year for fire blight risk assessment, we are comparing graphics from Maryblyt 7 and from the Cougarblight model as shown on our NEWA site. We are using the same weather data from our NEWA station to make these comparisons in both predictive programs.

CAUTION: The observations, conditions, and recommendations reported for Winchester, VA are provided as a guide to fire blight risk assessment only for the immediate area of the Virginia Tech AREC located six miles southwest of Winchester. Use of the information reported here for making orchard management decisions outside of that area is not our intent. Fruit producers outside of that area are encouraged to consult their state extension specialists for information similar to that provided here.
Maryblyt graphic for Winchester, Apr 21, 2017. Click to enlarge.
FIRE BLIGHT: Above is a cropped graphic from the Maryblyt 7 program, using Apr 5 as the date for first bloom open on Idared cultivar. Early-blooming cultivars still have some susceptible bloom, and later cultivars are near full bloom in the Winchester area. The temperature and rainfall data are current through Thursday evening, April 20. Predicted weather conditions are shown for April 21-26. The components of fire blight risk are indicated in the columns labeled B (blossoms open), H (degree hours for epiphytic bacterial populations), W (wetting by rain or dew), and T (average daily temperature 60 F or above). For infection to be predicted, wetting must occur after the EIP (epiphytic infection potential) reaches 100 or higher. Based on recorded temperatures and wetting, the risk column shows high risk and possible infection with any wetting Apr 11-12, 15-18 21, 24-25 and with slightly warmer than indicated temperatures and wetting Apr 13-14 and 18-20. Infection was indicated for Apr 12, and 15-17 and is predicted with wetting Apr 21. Note that risk can change quickly with unpredicted warmer temperatures and wetting. In high-risk situations, a protective streptomycin application is recommended ahead of predicted infection. Predicted cooler temperatures should reduce risk Apr 22-24, but will probably cause late bloom to persist into next week, and predicted warmer temperatures Apr 26-30 (not shown) will probably again bring high risk to late bloom. Continue to protect late bloom and bloom on newly-planted trees as needed.

The BBS column is tracking predicted symptom development for the first infection Apr 12 and symptoms are predicted to appear Apr 26. (Symptoms from artificial inoculation Apr 9 already appeared at our AREC by Apr 18). The CBS column indicates progression toward the appearance of canker margin symptoms due to extension of overwintering cankers from last year, which would be predicted to occur when that value reaches 100 Apr 23. Canker advancement cannot be prevented by chemical treatment at this time and the presence of symptoms will signal build-up of inoculum which could become a factor in the event of a trauma blight/shoot blight situation due to hail injury, etc. To offset the potential risk of shoot tip infection in an active fire blight year such as this one, apply the plant growth regulator, prohexadione-calcium (Apogee, Kudos), at late bloom. Shoot blight suppression results from hardening off of vegetative shoot growth starting about 10 days after the initial application. The fire blight outlook will be updated Monday, Apr 24.

Below is the graphic from the Cougarblight model as shown on our NEWA site. Note that we selected orchard blight history option as “Fire blight occurred in your neighborhood last year” and first blossom open date as 4/5/2017. (This date must be re-set each time this site is accessed). Cougarblight shows color-coded risk assessment as “Cougarblight 4-Day DH” which was “extreme” Apr 17-19, and for today, Apr 21, and remains “high” Apr 22-23. 
Cougarblight graphic for Winchester, Apr 21, 2017. Click to enlarge.
Early blossom symptoms (center) Apr 18 from artificial inoculation Apr 9.

Wednesday, April 19, 2017

Fire blight outlook April 19.


NOTE: This year for fire blight risk assessment, we are comparing graphics from Maryblyt 7 as in previous years, and also from the Cougarblight model as shown on our NEWA site. We are using the same weather data from our NEWA station to make these comparisons.

CAUTION: The observations, conditions, and recommendations reported for Winchester, VA are provided as a guide to fire blight risk assessment only for the immediate area of the Virginia Tech AREC located six miles southwest of Winchester. Use of the information reported here for making orchard management decisions outside of that area is not our intent. Fruit producers outside of that area are encouraged to consult their state extension specialists for information similar to that provided here.
 
Maryblyt graphic for Winchester, Apr 19, 2017. Click to enlarge.
 FIRE BLIGHT: Above is a cropped graphic from the Maryblyt 7 program, using Apr 5 as the date for first bloom open on Idared cultivar. Early-blooming cultivars still have much susceptible bloom, and later cultivars such as Rome Beauty are near full bloom in the Winchester area. The temperature and rainfall data are current through Tuesday evening, April 18. Predicted weather conditions are shown for April 19-24. The components of fire blight risk are indicated in the columns labeled B (blossoms open), H (degree hours for epiphytic bacterial populations), W (wetting by rain or dew), and T (average daily temperature 60 F or above). For infection to be predicted, wetting must occur after the EIP (epiphytic infection potential) reaches 100 or higher. Based on recorded temperatures and wetting, the risk column shows high risk and possible infection with any wetting Apr 11-12, 15-18 and 21, and with slightly warmer than predicted temperatures and wetting Apr 13-14 and 20. Infection was indicated for Apr 12, and 15-18 and is predicted with wetting Apr 21. Note that risk can change quickly with unpredicted warmer temperatures and wetting. In high-risk situations, a protective streptomycin application is recommended ahead of predicted infection.

Predicted cooler temperatures should reduce risk Apr 19-20 and 22-24, but will probably cause late bloom to persist into next week. Continue to protect late bloom as needed. The fire blight outlook will be updated Friday, Apr 21.

Below is the graphic from the Cougarblight model as shown on our NEWA site. Note that we selected orchard blight history option as “Fire blight occurred in your neighborhood last year” and first blossom open date as 4/5/2017. (This date must be re-set each time this site is accessed). Cougarblight shows color-coded risk assessment as “Cougarblight 4-Day DH” which is “extreme” Apr 17-18, and “high” Apr 19-23. Both predictive programs indicate a reduction in fire blight risk after Apr 18, but EIP values are somewhat higher in Maryblyt than for Cougarblight.

Cougarblight graphic for Winchester, Apr 19, 2017. Click to enlarge.

Monday, April 17, 2017

Continued risk of fire blight infection April 17!


NOTE: This year for fire blight risk assessment, we are comparing graphics from Maryblyt 7 as in previous years, and also from the Cougarblight model as shown on our NEWA site. We are using the same weather data from our NEWA station to make these comparisons.

CAUTION: The observations, conditions, and recommendations reported for Winchester, VA are provided as a guide to fire blight risk assessment only for the immediate area of the Virginia Tech AREC located six miles southwest of Winchester. Use of the information reported here for making orchard management decisions outside of that area is not our intent. Fruit producers outside of that area are encouraged to consult their state extension specialists for information similar to that provided here.
Maryblyt graphic for Winchester, Apr 17, 2017. Click to enlarge.
 FIRE BLIGHT: Above is a cropped graphic from the Maryblyt 7 program, using Apr 5 as the date for first bloom open on Idared cultivar. Most cultivars now have some susceptible bloom open in the Winchester area. The temperature and rainfall data are current through Sunday evening, April 16. Predicted weather conditions are shown for April 17-22. The components of fire blight risk are indicated in the columns labeled B (blossoms open), H (degree hours for epiphytic bacterial populations), W (wetting by rain or dew), and T (average daily temperature 60 F or above). For infection to be predicted, wetting must occur after the EIP (epiphytic infection potential) reaches 100 or higher. Based on recorded temperatures and wetting, the risk column shows high risk and possible infection with any wetting Apr 11-12 and 15-18, and with slightly warmer than predicted temperatures and wetting Apr 13-14 and 19-20. Infection was indicated for Apr 12, and 15-16 and is predicted with wetting Apr 17. Be aware that in situations where all other requirements for infection have been met except wetting, wetting from any spray application can provide the wetting trigger for infection to occur, and including streptomycin is suggested in such situations. In high-risk situations, a protective streptomycin application is recommended ahead of predicted infection.

As indicated with the changes in prediction for Apr 15-17 since the Apr 14 posting last week, risk can change quickly with unpredicted warmer temperatures and wetting. Particularly this week, continue to protect late bloom as needed. The fire blight outlook will be updated Wednesday, Apr 19. 
Below is the graphic from the Cougarblight model as shown on our NEWA site. Note that we selected orchard blight history option as “Fire blight occurred in your neighborhood last year” and first blossom open date as 4/5/2017. (This date must be re-set each time this site is accessed). Cougarblight shows color-coded risk assessment as “Cougarblight 4-Day DH” which is “extreme” Apr 16-18, and “high” Apr 19-20. Both predictive programs indicate a reduction in fire blight risk after Apr 18, but EIP values are somewhat higher in Maryblyt than for Cougarblight and that might be a factor for predicted risk later this week if weather conditions are more favorable for fire blight than currently predicted for Apr 19-22.
Cougarblight graphic for Winchester, Apr 17, 2017. Click to enlarge.

Saturday, April 15, 2017

Summary of early season fungal disease activity on apple and peach at Winchester.


Apple scab ascospores were first trapped Mar 10. Scab infection periods occurred on Mar 26-27: wet 15 hr at 46-60°, 0.23 in. rain. (also rust infection); Mar 27-28: wet 23 hr at 53-62°, 0.36 in. rain. (also rust infection); Mar 31-Apr 1: wet 23 hr at 41-48° with 0.95 in rain; Apr 3-4: wet 15 hr at 52-63° with 0.03 in rain. (also rust infection); Apr 6-7: wet 14 hr at 50-55° with 0.53 in rain. (also rust infection).
Apple scab pressure has been significant, with five infection periods in the past three weeks. Lesions from the March infection periods will be expected to appear in the next week and conidia will then be produced for heavy secondary infection. These five infection periods from Mar 26 to Apr 7 came with enough total rainfall to challenge weathering capabilities of protective fungicides.
Cedar-apple rust and quince rust have been active for about two weeks. Pink to petal fall is the peak time for susceptibility to quince rust. We suggest EBDC fungicides as routine protectants for rusts and scab, but always include an SI fungicide (Rally, Rhyme, Inspire Super, Indar) for after-infection rust control if there is any doubt about lack of protective residue.
Apple powdery mildew conidia were available Mar 27. The image of mildew below illustrates heavy sporulation of a primary infection source of inoculum. Any mild “dry weather “ day above 53° is suitable for mildew infection. From Mar 27 to Apr 14 we have had at least nine mildew infection days.
Primary powdery mildew infection on Ginger Gold apple.
Note heavy sporulation on Apr 14, 2017.
Early peach leaf curl symptoms were observed at our AREC Apr 14 (below). This infection occurs with extended wetting soon after bud swell. In our test plots, a protective fungicide applied Feb 28 gave excellent control, but the same fungicide applied Mar 9 was less effective.
Leaf curl symptoms on Redhaven peach Apr 14, 2017.
Peach scab overwinters in lesions on peach shoots (below). Lesions are now producing spores, and it is important to maintain a protective fungicide residue to prevent infection during extended wetting periods over the next 4-6 weeks. Infection can require as much as 7 weeks to appear on fruit.
Peach scab lesion on a Redhaven twig Apr 14,2017.
Close proximity to the young fruit makes it a challenge to protect against infection.

Friday, April 14, 2017

Fire blight risk outlook, April 14-20.

NOTE: This year for fire blight risk assessment, we are comparing graphics from Maryblyt 7 as in previous years, and also from the Cougarblight model as shown on our NEWA site. We are using the same weather data from our NEWA station to make these comparisons.

CAUTION: The observations, conditions, and recommendations reported for Winchester, VA are provided as a guide to fire blight risk assessment only for the immediate area of the Virginia Tech AREC located six miles southwest of Winchester. Use of the information reported here for making orchard management decisions outside of that area is not our intent. Fruit producers outside of that area are encouraged to consult their state extension specialists for information similar to that provided here.
Maryblyt graphic for Winchester, Apr 14, 2017. Click to enlarge.
FIRE BLIGHT: Above is a cropped graphic from the Maryblyt 7 program, using Apr 5 as the date of first bloom open on Idared cultivar. Early cultivars are near full bloom and most cultivars have some bloom open. The temperature and rainfall data are current through Thursday evening, April 13. Predicted weather conditions are shown for April 14-20. The components of fire blight risk are indicated in the columns labeled B (blossoms open), H (degree hours for epiphytic bacterial populations), W (wetting by rain or dew), and T (average daily temperature 60 F or above). For infection to be predicted, wetting must occur after the EIP (epiphytic infection potential) reaches 100 or higher. Based on recorded temperatures and wetting, the risk column shows high risk and possible infection and possible infection with any wetting Apr 11-12, and with slightly warmer than predicted temperatures and wetting Apr 13-14 and 17-19. Infection is predicted with wetting Apr 16. Be aware that in situations where all other requirements for infection have been met except wetting, wetting from any spray application can provide the wetting trigger for infection to occur, and including streptomycin is suggested in such situations. In high-risk situations, a protective streptomycin application is recommended ahead of predicted infection.

Be aware that risk can change quickly with unpredicted warmer temperatures and wetting. The fire blight outlook will be updated Monday, Apr 17.

Below is the graphic from the Cougarblight model as shown on our NEWA site. Note that we selected orchard blight history option as “Fire blight occurred in your neighborhood last year” and first blossom open date as 4/5/2017. This date must be re-set each time this site is accessed. Cougarblight shows color-coded risk assessment as “Cougarblight 4-Day DH” which remains “extreme” through Apr 12-14, and “high” Apr 15-19. (EIP in Cougarblight lacks only one unit for Apr 16, which would move the risk to “extreme” for Apr 16). Comparable EIP values and trends are shown for both predictive programs each day this week. 
Cougarblight graphic for Winchester, Apr 14, 2017. Click to enlarge.