Janna L Beckerman

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

49 articles by this author

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Figure 1. Bitter rot, 2018. Note the mummy I hold personally responsible for this

After second cover, the most serious apple pathogens are generally less active, as terminal buds have set, leaves have hardened off (and are now less susceptible) and weather is usually getting hotter and drier. Just not this year!!! This is the time when we often dial it back a notch in the fungicide department. One word of advice for this year: Don’t! If you are still within the 77-day pre-harvest interval, get that last application of mancozeb on while you still can. It is one of, if not the best protectant against the summer rots, along with controlling scab. When you can no longer use mancozeb, switching over to ziram (with a 14 d PHI) or captan (see label as PHI varies) as a tank-mix or rotation partner is necessary to protect fruit during these frequent and heavy summer rains for the remainder of the season. During a record wet[Read More…]


Fig. 4. A river runs through it. Photo by Janna Beckerman.

Current wet weather is increasing the risk of Phytophthora diseases in the orchard. Phytophthora is a major problem on apples and pear; stone fruit are also susceptible, with plums being the most resistant to this disease. In addition to excessive soil moisture and flooding, moderate temperatures, wounds (mechanical or through herbicide damage), and rootstock susceptibility all factor into Phytophthora infection. Early spring symptoms of this disease include delayed bud break, smaller than normal and/or discolored leaves, along with twig or small branch dieback. Trees often look ‘unthrifty’ and sparse (Fig. 1). Unfortunately, these symptoms can be mistaken for nutrient deficiency, winter injury, or even herbicide (Fig. 2) or flood damage. It can also resemble fire blight infection of the rootstock. Examination of the crown is an essential aspect of diagnosing this problem. Peeling away the bark may reveal discoloration, cankering or rotting at or below the graft union, with healthy[Read More…]


Fig. 1. Missed applications can result in serious scab. Photo by Janna Beckerman.

Apple Disease Management Constant rain has resulted in a great scab season. Again. Keep in mind that infection develops really slowly under these (mostly) cool, wet conditions. This means symptoms from primary infection may have just started to be visible and that we are already going into secondary infection even as primary infection continues. With the constant rain, and infection, I want to warn people from thinking ‘Fungicide resistance!’, as opposed to what really happened—heavy rains that washed off any trace of fungicide, plus a long, cool wet infection period that delayed symptom development. Hopefully, everyone was able to get into their orchard and get their applications on to protect against scab, powdery mildew and rust. And of course, bitter rot. Black Knot Prune out, remove or dispose of any and all visible black knot galls. Sanitation is a cornerstone of management! Ascospores of the black knot fungus, Apiosporina morbosa,[Read More…]


Apple Phytotoxicity Flint Regulaid blossom burn.

Apple Disease Management Notes for April For those at tight cluster through pink: Assuming trees have less than 3” of new growth, early applications of apogee will help prevent fire blight in what is shaping up to be a cooler, wet spring. With temperatures flirting with 70, fire blight needs to be on your radar and you can still apply Apogee. All that new, succulent growth needs to be protected as it develops to prevent primary scab. Protectant fungicides for control of scab at this stage include mancozeb and captan. As an added bonus, both also protect against the summer rots, and mancozeb also protects against rust. Current work from our field trials suggests that the infection period for the summer rots is earlier than previously suspected. Early applications improved bitter rot management, in particular. For powdery mildew issues, include any FRAC 3 (Rally, Indar, Procure or Rhyme) OR FRAC[Read More…]


Sweet cherry is crop that continues to be of great interest to Indiana growers. It also continues to be a challenge due to bacterial canker, caused by Pseudomonas syringae. This bacterium is a significant pathogen of young sweet cherry trees killing 10 to 20 percent of the trees in new orchards within 5 years of planting. I’ve modified Dr. Robert A. Spotts, OSU Mid-Columbia Agricultural Research and Extension Center, Hood River, OR, suggestions for the integration of several techniques that are more appropriate for Indiana growing: 1.Do not interplant new trees with old trees, which are major sources of P. syringae. Think about it! Any old, infected trees serve as inoculum to infect new trees! Keep irrigation water off the part of the trees above ground as much as possible for the first 2 or 3 years after planting. If irrigating, consider withholding water in late summer so trees will[Read More…]


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Just like other commodities, “generic” versions are increasingly available for many common fungicides as patents expire on various proprietary active ingredients. By law, generic products must contain the same amount of active ingredient as the original fungicides, but the formulation may be different. As a result, confusion continues as formulation of a fungicide is proprietary information that may not be included in a generic product. For maximum effectiveness, formulation describes the processes performed to the active ingredient affects to improve efficacy. This process can include reduction to appropriate particle size, the addition of ‘inert ingredients’ that alter the characteristics of the fungicide, and improves delivery and persistence of the pesticide. Growers are familiar with this in the myriad of glyphosate (i.e., Round-Up(R)) products available, and their differing performance on the diversity of weeds. Generic products tend to be more economical than brand name products, but most have not have been[Read More…]


The University of Minnesota Department of Horticultural Science takes a fresh, encouraging new look at growing fruit in the home garden. This guide will help gardeners decide which fruits are right for their gardens and their lifestyles, taking readers through every step from planning, choosing cultivars, and planting, to harvesting and pruning. Readers will find information on the major pests to look out for, and simple tips on how to deal with them; or better yet, prevent them. Growing Fruit in the Northern Garden  


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…]