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Fruit Blog is a fire blight alert blog that runs throughout bloom for the Lake Ontario region. This service is brought to you by the Lake Ontario Fruit program and the Tree Fruit and Berry Pathology program, which are part of Cornell Cooperative Extension. The blog will be updated daily and will begin as apple bloom approaches. Check back frequently!

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• 5/08/07:Fire blight alert: In Williamson and other inland sites across the region, pears began to bloom. I ran a pear fire blight prediction using Maryblyt and found that if the first bloom was yesterday, May 7, we will exceed the threshold of degree hours (198 dh base 65F) for a blossom blight infection if we also get a shower on Thursday. Watch for bloom on pears to start fire blight models. Those of you with Asian pears, look for bloom even earlier but no degree hours accumulated until this Monday, so Asian pears are also at risk of blossom blight by Thursday if we get the predicted shower.
  
  Any apples that also came into bloom yesterday are also at high risk for blossom blight on Thursday if we get a shower, but even if apples do not start to bloom until Wednesday, if we get high temperatures in the upper 70’s on Wednesday, they will be very close to the dh threshold. If your orchards are just a couple degrees warmer on Wed and Thursday, it will also be a very high risk of blossom blight.
  
  Order streptomycin now so you have it on hand when you need it. The warehouses are not necessarily stocking things on speculation – you need to communicate with your supplier about the risk of fire blight coming toward the end of the week.

 

• 5/10/07: Fire blight alert: In Williamson and other inland sites across the region, pears began to bloom on Monday. Idared and Gingergold, 20 oz. were in first bloom in inland sites on Tuesday. Asian pears are also at risk of blossom blight today if we get the predicted shower.
  
  In orchards with first bloom on Monday and Tuesday, we generated enough heat units yesterday for a fire blight infection with the showers predicted for today, Thursday. Any apples that also came into bloom as of Wednesday are also at high risk for blossom blight today if we get a shower.

 

• 5/11/07: Fire blight alert: Yesterday’s showers brought a fire blight infection for most apples and pears in bloom in orchards close to Rt 104 and south in Monroe, Orleans, and Niagara Counties. In these sites, if that first bloom opened May 7, 8 or 9, you reached the degree hour threshold for an infection to occur on May 10. In these sites, if you had more than a .1 inch of rain on May 10, and a high temperature in the mid-70’s
  for yesterday and today, Maryblyt is predicting an infection for today as well if no strep was applied yesterday. Most growers in these locations applied streptomycin on May 9 or 10, and with the forecast of temps only in the low 60’s for the weekend, the risk ofblossom blight will decrease. I will reassess the risk on Monday as they update the forecast.

 

• 5/16/07: Fire blight alert:The high temperatures across the region ran from 81-85 yesterday. In sites
  just along the lake where the high temperature was only 80-81, the Maryblyt model did not predict an
  infection for yesterday due to the lower temperatures along the lakeshore in Appleton on Monday. The
  same situation occurred for Williamson. The models predicted an infection when we enter a high
  temperature of 82. Remember there are sites on your farm that are warmer than others – are these
  where you typically get fire blight in other seasons?
  
  In any orchards where you have active cankers, I am concerned about the gusty conditions yesterday
  with driving rain that could result in some “trauma blight” of the clusters, that will be mistaken
  eventually as blossom blight when the symptoms start to appear.
  
  The rain should move out this morning, and then spray conditions will improve so you can get out and
  apply streptomycin in pears and susceptible apple varieties, and include it with your fungicide
  treatment.
  

 

• 5/18/07: Fire blight alert?:The fire blight models predicted an infection on Tuesday, May 15 in most
  parts of the LOF region, except right along the lakeshore. In orchards with active cankers, I will not
  be surprised to see some trauma blight developing an a week or so. With the high temperatures only in
  50’s and 60’s for the rest of the week and weekend, there is no risk of blossom blight at this time.
  Temperatures will warm up into the 70’s again starting Tuesday and the risk will be a bit higher by the
  middle of next week. I am seeing several varieties like Gala, Romes, Greenings, asnd other late
  blooming varieties with plenty of unopened blossoms. These orchards will be the blocks to treat next
  week if we get warm temperatures again.
  
  I am also seeing a lot of new apple plantings with lots of blossoms. Either go through the planting and
  remove these blossoms, or treat with strep when you are treating bearing orchards. The new orchards
  can be treated with the low label rates of copper as well to prevent infection from neighboring
  orchards.

 

• 5/22/07: Fire blight alert?:The fire blight models and the weather forecast are predicting another blossom
  blight infection after we regain enough heat units by the end of Wednesday. There are still plenty of
  blossoms yet to open on varieties like Jonagold, Gala, Rome, etc. that will require another application
  of streptomycin if we actually get a wetting event through heavy dew, spray, or rain as predicted on
  Friday. The more blossoms open at the time of sprya application, the more protection you will get. If
  you treat as early as Wednesday, and more blossoms open after application, there will be enough heat
  generated for Thursday and Friday to have another infection. But if you treat on Thursday, that will
  probably get you through this high risk period. Don’t forget about your new plantings!

 

• 5/24/07: Fire blight alert?:We have accumulated enough degree hours as of yesterday and by the end of
  today, will be in the 500-600 degree hour range. This is the kind of weather that experience tells us
  that even “non-susceptible” varieties can be infected. Gala, Fuji, Jonagold, Macoun, Romes,
  Goldens, still have significant bloom left even in inland sites to result in a significant blossom blight
  infection if we get a wetting (shower, spray, or heavy dew). Along the lake there are even more
  blossoms present on other varieties including Crispin. Drive around your farm and note which apple
  varieties still have blossoms left and blossoms left to open. In “playing” with the model, if you treat
  with streptomycin today with your petal fall sprays, and there are still blossom yet to open, you will
  gain enough heat after treatment to result in another infection after the 80 F on Saturday. If there is no
  wetting event today and you do not treat until Friday, it will get you through the weekend without the
  need for a second spray during late bloom. These are just guidelines are dependent upon high
  temperatures in the mid-upper 80’s even close to the lake. Lakeshore sites may not get that warm, but
  since we have few automated weather sensors that close to the lake, it will be difficult to call. It is a
  southerly system and typically strong enough to warm up orchards very near the lake. Don’t forget
  about your new plantings!

 

• 5/26/07: Fire blight alert?:Not much has changed since my last fire blight update. This time the
  forecasters have been pretty accurate. In locations just half a mile inland, in varieties that have not
  been treated with streptomycin, we have accumulated 600-700 degree hours in the last 4 days of warm
  temperatures. This is the kind of weather that experience tells us that even “non-susceptible”
  varieties can be infected.
  
  Susceptible varieties Gala, Fuji, Jonagold, Macoun, Romes, Goldens, and more still have significant
  bloom left even in inland sites to result in a significant blossom blight infection if a wetting event
  occurs (shower, spray, or heavy dew). We did get a few scattered showers across the region yesterday
  afternoon, and some locations had leaf wetness measured from dew.
  
  For those of you who sprayed Thursday, you have re-accumulated enough degree hours to break the
  threshold on any blossoms that were not yet open on Thursday but open Friday. This may be the case
  in Gala and Fuji with a lot of bloom on 1 year old wood and trees planted this year! In this case, I am
  sure most of you would rather spray Saturday then Sunday and it looks like spray conditions are good.
  
  If you waited until Friday to treat with streptomycin (too bad the spray conditions weren’t quite as
  good), you are home free through the weekend.
  
  Along the lake there are even more blossoms present on other varieties including Crispin. You folks
  right along the lake accumulated enough degree hours on Thursday, and at least along the lakeshore of
  Niagara County had a shower last evening to result in an infection. If you treated Thursday, you will
  accumulate enough degree hours again today for another potential infection. If more showers come
  through , you will have another infection and will need to treat. If you sprayed on Friday, May 25, you
  are good through the weekend. Do not discount the potential for dew in low lying spots in the
  orchards!

 

• 5/24/07: Fire blight!: Continue to watch new plantings since some later plantings and late planted replacement
  trees are just now coming into bloom. We will continue to have sufficient heat for high risk of
  infection in these trees still in bloom. Either remove blossoms or spray with strep. A low labeled rate
  of copper is also an alternative in these young trees. Canker blight symptoms will also appear now
  and the weather conditions are conducive for bacterial ooze from these infections. Remove these
  infections now before they contribute to shoot blight conditions.

 

• 6/4/07: Fire blight!:Scout orchards now for fire blight. And continue to treat new plantings in bloom for
  blossom blight. If scouting in Romes or Fuji, you will also find the signs of Nectria twig blight which
  resemble fire blight. It can be distinguished from FB by the orange coloration and pimple-like
  structures at the base of this year’s shoot growth and should be quite plentiful with the wet fall of last
  season. Canker blight symptoms are also apparent now and the weather conditions are conducive for
  bacterial ooze from these infections. Remove these infections now before they contribute to shoot
  blight.

Fire Blog is creation of this site and team members of the Lake Ontario Fruit Program, CCE, of Western NY