Janna L Beckerman

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

42 articles by this author

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Apple Honeycrisp bitter rot sporulating

As harvest continues, so does the summer rot saga, especially bitter rot. Multiple orchards are reporting significant to complete loss of Honeycrisp throughout the Midwest, in addition to other varieties. Honeycrisp is by far the worst hit, but its seems that Golden Delicious, Granny Smith, Cameo, Ida Red, Empire, Fuji and Gala have had problems in the past. If you are having problems on other varieties, please let me know. We have a trial underway to see if a preharvest application of captan or Merivon helps improves long-term storage options. I’ll have the data to you for the winter horticultural congress in Indianapolis.


Susan Brown of Cornell probably said it best: “The performance and attributes of Honeycrisp are varied and can be grouped under the heading, ‘The good, the bad, and the ugly.’ The ‘good’ refers to a great name for marketing and excellent texture, crispness, and juiciness. The ‘bad’ refers to coloring problems, appearance defects, and susceptibility to an undiagnosed leaf dis- order. The ‘ugly’ refers to bitter pit, scald, soft scald, and a tendency to ferment due to skin permeability problems.” More than 25 years after the release of Honeycrisp, we still don’t have definitive answers. We are already experiencing numerous reports of Honeycrisp (and other apple) yellows this year (Fig. 1a,b,c). This disorder is a genetic peculiarity of Honeycrisp (and apparently a few other varieties) and is believed to be caused by excessive buildup of carbohydrates in the leaves (Snyder-Leiby and Wang, 2008). Yellowing is often most severe on trees[Read More…]


Fig. 1. Bitter pit and lenticel rot often appear at the calyx end of the fruit. Photo by Janna Beckerman

With weird weather often comes weird physiological disorders (on top of our summer fruit rots). Often confused with hail injury, disease or insect damage, these physiological disorders are marring the appearance of many apples. Symptoms of bitter pit include circular or even irregular sunken spots on the fruit surface, beneath brownish or streaked dead regions (Fig. 1). Note that the damage can be separated from the skin surface. Symptoms may be mistaken for hail damage, or any of the below problems. A key diagnostic feature is that hail usually affects only one side of the fruit, whereas bitter pit is more severe on blossom end of the fruit. Some varieties, like Honeycrisp, are more prone to this disorder, whereas hail will impact (literally) all varieties of fruit. Bitter pit can show up throughout the orchard, not just the edges. Cork spot is another physiological disorder affecting outer portion of the[Read More…]


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Stone Fruit: At our orchard, we lost our stone fruit with the -20 degree F temperatures this winter. For those of you fortunate enough to have fruit, frequent and heavy rain present problems multiple problems, namely bacterial spot and brown rot. Three weeks before harvest, cease bacterial spot sprays, even though bacterial spot may continue to be an issue with this hot wet weather. You can still manage brown rot. To maintain and protect fruit, be sure to rotate chemistries by FRAC Code to minimize the risk of fungicide resistance. Some options to consider (choose one from each column and then choose a different column-do not repeat a column back to back, and always used the highest labeled rate).


Glomerella leaf blight seems to be rearing its ugly head. Symptoms include lesions with concentric rings in them that can grow together and give the leaf a blighted appearance (Fig. 1). Leaves may yellow and fall off (Fig. 2) and may appear like Golden Delicious necrotic leaf blotch on a variety of apple cultivars (Fig. 3). Before anyone panics, Glomerella is not a new pathogen, but the sexual state of a fungus that was first identified it its asexual state and was named Colletotrichum. Fungi known to infect apples and belonging to this group (genus) cause bitter rot. Previously, the bitter rot pathogens were divided into two species complexes: C. acutatum and C. gloeosporioides. Recent work in Kentucky found five different species of Colletotrichum associated with bitter rot: C. fioriniae, C. nymphaeae, C. siamense, C. theobromicola, and C. fructicola. The relationship between bitter rot and Glomerella leaf spot, if any, is not[Read More…]


Figure 1. The branch stub serves as a wound that enables a pathogen, in this case, Nectria spp., to infect. Photo by Janna Beckerman.

Diseases that affect the twigs, branches, and the main trunk of a tree are referred to as cankers or blights. Canker diseases  can be a serious problem in the orchard, vineyard, berry or bramble patch when they are not properly managed, and even when they are. All woody plants can be infected by canker pathogens. Cankers appear as a general sunken area of darkened tissue on the twigs or branches, often surrounding a branch stub(Fig. 1). Many canker pathogens produce perithecia, which contain sacs of spores (asci) that forcibly release the spores when the conditions are right. The perithecia are easy to find on the surface of the canker (Figure 2). As the canker grows, the twig or branch may become girdled, causing the wilting and death of the leaves past the point of infection on the tree. On stone fruit, this can cause gummosis, too (Fig. 3). What causes[Read More…]


Those of you lucky enough to still have a crop. Drier than usual weather means the risk of scab and bacterial diseases is low, but powdery mildew is higher. Although Rally and Topguard provide excellent control of powdery mildew, Flint extra, Luna Sensation and Merivon all provide excellent control of not only powdery mildew, but against scab and brown rot, should weather turn wet.  


Fig. 2. Juniper rust, specifically, cedar-hawthorn rust. Photo by Janna Beckerman.

From one of the coldest Aprils to one of the hottest Mays, what will June bring us? So far, apple scab has been less of a problem than usual, but powdery mildew seems to flying under the radar for many orchards. Keep your eyes out for the characteristic leaf curl (Fig.1). Varieties like Jonathan, JonaGold, Cortland, GingerGold and SunCrisp, are very susceptible. Due to the dry weather, many growers switched to a captozeb program, which is excellent against scab, but doesn’t do anything for powdery mildew, or very little against rust. Speaking of rust: Dry weather has delayed not only ascospore ejection of scab, but also those orange, gelatinous kooshballs of spores (Fig. 2). I don’t recall the last time I saw any telial spore horns (aka kooshballs) in June, but they were still going like gangbusters on June 1 here. For those in central Indiana to parts north, all[Read More…]


Fig. 3. Brown rot of plum. Photo by Steve Goodwin.

What??? Yes, thanks to the Return Bloom Fund and the Meigs Farm Team, we have a small planting of three varieties of plum: Early Shiro, Green Gage, and Ruby Queen. Did you know in Australia, some varieties are retailing at $15.90AU per kilogram (or $7.22 per pound)? Most Midwesterners only know those hard, tasteless things disguised as plums, hailing from California, and delivering only disappointment. Fresh plums not only taste good, but are good for you, regardless of variety—they are high in fiber and antioxidants. And let us not forget, plums are a principle component in ‘a warrior’s drink’. “NuqDaq ‘oH puchpa’’e’?” Although these plums will be used to study brown rot (Fig. 3), I hope I can convince a few of you that planting plums isn’t just good for the soul, but the bottom line. Live long and prosper!


rat-tail blooms

In case you blinked, we went from green tip to bloom in about three days, and by the time you read this, we will have passed through the blossom blight period. For most of the state, the late spring consisted of cool, dry weather that was not conducive to blight infection in the northern half of the state. The southern half of the state was only slightly more conducive for infection. This means that any strikes seen in the next few weeks probably came from damage from last year. Since last year was unusually wet, with a lot of susceptible rat-tail blooms, it is most likely that any fire blight infections observed as shoot and canker blight can trace their beginnings to rat-tail blooms of last year (Fig. 1). What to do now? Until a terminal bud has formed and growth has ceased, I do not recommend pruning out strikes[Read More…]