Janna L Beckerman

Professor of Plant Pathology
Department of Botany
Area(s) of Interest: Ornamental and Fruit Diseases
Janna L Beckerman's website

30 articles by this author

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Temperatures below -15°F generally kill powdery mildew infected buds. For those of you who had a milder winter, protecting susceptible varieties like Jonathan, Ida Red, Enterprise, Staymen, Granny Smith, and Ginger Gold, be sure to protect at tight cluster, pink, bloom, petal fall and first cover. Remember that fungicide protection is needed until terminal buds are set. As long as resistance isn’t an issue, Rally, Procure and Indar, are the most effective DMI fungicides; Merivon, Pristine, and Luna Sensation (7+11 fungicides) or Flint Extra, Flint, or Sovran (11).


If you had problems with fire blight last year, this is for you: The best preventative measures for fire blight are the application of streptomycin at bloom to prevent blossom blight and the application Apogee at petal fall to reduce shoot blight. Yes, Apogee is expensive. It is worth every single penny. Apply streptomycin just as blossoms begin opening and repeat every 3-4 days if weather is favorable or blossom blight infection persists. Streptomycin is most effective when applied the day before or the day of an infection event. Be especially diligent in your fire blight program if you have blight susceptible varieties (Jonathan, Gala, Ginger Gold, Ida Red, Jonagold, Fuji, Lodi, etc.) in combination with M-26, M-9 and/or Mark rootstocks and/or interstems. For young trees, excess nitrogen to drive growth makes trees more susceptible to fire blight, especially Evercrisp and other Fuji hybrid cultivars.


Calculate the 77 days to harvest date for each of your cultivars and make the final application of EBDC fungicide (Dithane M-45, Manzate 200, Penncozeb, Polyram, Roper) on that date to take full advantage of the excellent control these fungicides provide for bitter rot, black rot, and white rot, in addition to sooty blotch and flyspeck.  This recommendation applies only to growers who used the low rate of mancozeb – 3 lbs/acre.  Refer to page 28 of, “2018Midwest Fruit Pest Management Guide“, for further information.


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Check list: ~Indiana Disease management program for apples for 2018 is available at: https://www.extension.purdue.edu/extmedia/BP/BP-201-W.pdf This information is identical to the Midwest fruit pest management guide, but provided in a table format and includes Fungicide Resistance Action Committee (FRAC) Codes, REI, PHI and efficacy information for each product (Fig. 1). ~Reducing overwintering inoculum for apple scab: For orchards with less than stellar scab control last year, inoculum reduction before the growing season begins is an integral component of scab control. In the spring, two approaches can be used to reduce overwintering scab: An application of a urea spray (42 lb/A in 100 gal of water/A) sometime before green tip with a penetrant surfactant like LI700 or Wet Betty, and/or Shredding leaf litter with a flail mower Rake or vacuum up leaves, and remove them from the orchard (home orchard only) For growers in southern Indiana who may be already experiencing green[Read More…]


For those of you lucky enough to still have a peach crop: Early shuck-split and shuck-fall sprays are critical for peach scab control. The first spray should be applied about one week 30after petal fall.  Do not wait until the shucks have slipped to begin this program.


Summer rots continue to rear their ugly heads (Fig. 1). This year, we are even seeing them on late season apples like Evercrisp    (Fig 2) and GoldRush. On the plus side, we are seeing some level of control with all fungicides in our trials (data will be presented at the Indiana Hort Congress); unfortunately, on highly susceptible varieties like Honeycrisp, we need to do more research to figure out how to better control these pathogens. Treatments that provided reasonable control in Golden Delicious suffered 10 times more infections on Honeycrisp. Future research will examine the role of timing and fungicide choice on infection. As always, please contact me if you are seeing new problems, increasing severity of problems, or you can surprise me and tell me what a great year you had! As you can see, Jojen loved the harvest, and has decided like most children, that Honeycrisp and[Read More…]


Fruit rots continue to pose a problem for those of us in the wetter parts of the state. Frequent rains and warm temperatures really set the stage for bitter rot, black rot, white rot, and even brown rot. Any rain event that produced more than 2” of rain would remove the majority of fungicide, meaning that harvested fruit is going into the storage bin unprotected from these pathogens. If possible, a fungicide like Merivon or Pristine, with a zero day preharvest interval will provide protection in storage. However, fruit that may have looked clean at harvest could be infected, and any infected fruit will develop lesions over time. At this stage, damage control is limited to scouting bins, and removing infected fruit as it develops. Remember that postharvest applications of fungicide will not “cure” fruit that is already infected! Some key points to minimizing storage rots include: Using clean bins[Read More…]


In 1907, Thomas Burrill wrote that regarding bitter rot, “There was nothing to do but to helplessly submit to the inevitable.” However, he continued and stated “that what formerly seemed incomprehensible is easily understandable.” Some key points he touches on regarding the management of bitter rot are weather conditions and sanitation. Obviously, there is little that can be done about the weather. The bitter rot pathogen complex grows well in hot, wet weather.  I say complex because it turns out there are several different species of Colletotrichum causing this disease (or causing Glomerella leaf spot). In fact, even the complex is complex, with the previous delimitation of Colletotrichum gleosporioides and C. acutatum both now described as complexes consisting of several different species each! What is interesting, 110 years later is that little has changed by way of management options: “(1) cutting of and handpicking the cankers and old mummies; and[Read More…]


Russetting of the skin

Since 2012, apple powdery mildew(PM) has been part of new normal of apple growing in Indiana. As many of you remember (but would like to forget), 2012 was the year when much of the state lost the crop due to a late season freeze. This was then followed by one of the driest years on record. The loss of fruit resulted in many growers greatly reducing their fungicide applications, or using just captan or mancozeb, which, although effective against scab, are not effective against powdery mildew. This led to a build-up of PM inoculum, and continued management issues surrounding this problem. Powdery mildew symptoms can range from the subtle (Figure 1) to the incredibly obvious (Figure 2), and everything in between. As these Honeycrisp terminal buds break due to excessive rainfall, new growth is very susceptible to powdery mildew. Cover sprays should include either Pristine, Merivon or Luna Sensation, Sovran[Read More…]


It may seem like the worst is over, but apple growers should continue to be vigilant and apply fungicides even as we approach the end of the ascospore discharge period. Leaves are still highly susceptible to both primary and secondary apple scab infection until the terminal bud has set and the leaves have hardened off. Our cool, wet, crazy spring resulted in the late formation of primary scab lesions coupled with a long growth period, meaning more opportunity for scab infection. As a result growers that scouted earlier and found no scab may think their orchard is a lot ‘cleaner’ than it really is. Those hard-to-detect primary lesions can churn out 95,000 conidia per lesion! This makes it difficult to determine if the later lesions are late primary infections or actually secondary infections. Let’s face it: No one cares except the plant pathologists. Upshot: Scab control is really, really important[Read More…]