Spots on Honeycrisp Apples: What are They and How to Differentiate Them?
Zarah Ahmed, Candidate for B.S. in Physiology and Neurobiology & Macarena Farcuh, Ph.D., Assistant Professor and Extension Specialist University of Maryland, College Park
What are physiological disorders?
Physiological disorders can be defined as abnormal growth patterns that can impact the external and internal conditions of fruit. They are not caused by insects, pests, or mechanical damage, but rather by environmental factors or production practices (pre- and postharvest). The development of physiological disorders will directly impact fruit quality, thus increasing fruit losses and reducing fruit marketability and profitability.
Particularly for Honeycrisp apples, there are different types of physiological disorders that can develop both on the tree as well as during storage, but only some of them are characterized by the development of spots in the skin and sometimes flesh. Some of these include bitter pit, lenticel blotch pit and lenticel breakdown. Being able to differentiate among these will be beneficial in identifying them properly and working to prevent their future incidence.
By Jerry Brust, IPM Vegetable Specialist, University of Maryland
This is just a reminder with the usual summer weather we have had lately with stretches of very high temperatures and the occasional very heavy down pour we have had over the last few weeks blossom end rot can become a real problem in tomatoes. Sunny days will suck water through a plant quickly and the downpours will disrupt calcium movement through the plant. The key is to try and maintain consistent soil moisture while the fruit is developing. Easier said than done I know, but soil moisture levels need to be monitored as best as they can. When you see something like figure 1, with all the tomatoes on a cluster with blossom end rot you know the soil moisture fluctuated greatly over a fairly long period of time. Applying some foliar calcium sprays may help, but the applications can’t overcome poor soil moisture management.
Fig. 1 All the tomatoes on this one cluster have blossom end rot—indicating poor soil moisture management. Photo By J. Brust.
Strategies for Effective Management of Botrytis and Anthracnose Fruit Rot in Strawberries
Dr. Mengjun Hu, Univ. of Maryland, and Kathy Demchak, Penn State Extension
Managing gray mold (Botrytis) on strawberries is increasingly challenging because of fungicide resistance development, plus a new Botrytis species that is less susceptible to fungicides is becoming common in the mid-Atlantic region. Resistance to certain fungicides is also a problem in management of anthracnose fruit rot. This article describes disease management strategies designed to slow further resistance development, while also providing specifics for managing our two most common fruit rots.
Gray mold on strawberry. Photo: Kathy Demchak, Penn State Extension
First, what’s new with Botrytis. There are at least 4 species of Botrytis that can infect strawberries, but only two of them have been commonly found in the region. Botrytis cinerea, the species traditionally infecting strawberries, is present nearly everywhere and affects many horticultural crops. Recently another species, Botrytis fragariae, has also been found and as its name indicates, is more specific to strawberry plants. It appears to overwinter on strawberry plant tissue, and preferentially colonizes blossoms early in the spring, causing them to “turn brown and dry up”. While sometimes only one of these species is present, both can be present at the same time in a field and even in the same blossom. Using certain fungicides selects for resistant strains of either species, and also preferentially selects for one species over the other. This means that both species have resistance to multiple fungicide groups, and both species can survive in fungicide-treated fields.
How can you tell if the newer species of Botrytis might be present in your fields? While B. cinerea (the traditional species) is often isolated from both flowers and fruit, B. fragariae (the new one) is often isolated from flowers, and it has been shown that B. fragariae infection was much more aggressive on strawberry flowers than fruit. If you see larger-than-usual numbers of blossoms turning brown and shriveling (not to be confused with frost damage, which blackens the center of the flower), it may be prudent to choose fungicides as if B. fragariae presence had been confirmed in your field. If you see no more symptoms on the flowers or buds than usual, you may be able to assume that the new species isn’t present, or at least not to a great extent.
Despite cooler temperatures during the past few days, apple scab(Venturia inaequalis) spores continue to mature. A significant apple scab infection event is forecasted April 5 to 7, 2022, in Pennsylvania and surrounding area. For those with green tissue present on their apple trees, protection is necessary for this event.
The apple scab fungus overwinters in infected leaves. As it warms up in the spring they mature and produce spores that are discharged into air currents and carried to developing apple buds. The disease negatively affects fruit size and quality (due to blemishes and poor ripening). Over time, repeated defoliation from the disease reduces tree vigor, growth, and yield.
Apple scrub leaf lesions. Photo by Penn State Department of Plant Pathology & Environmental Microbiology Archives , Penn State University, Bugwood.org
Apple scab produces gray-to-olive green lesions on the leaves ( as seen above), but may also be seen on blossoms, sepals, petioles, pedicels, and fruit. On leaves, lesions first appear on the undersides of young leaves in the spring as they unfold and are exposed to infection. Leaves are susceptible to infection for about 5 days after they unfold. Fruit may become infected at any time in its development. Typical fruit lesions are distinct, almost circular, rough-surfaced, olive-green spots up to ¾ inch in diameter.
Written by Neith Little, Urban Agriculture Extension Agent Reviewed by Dr. Gerald Brust, IPM Vegetable Specialist and Andrew Kness, Agriculture Extension Agent
Phytophthora blight plagues peppers and melons
The hot wet weather this summer has been the perfect conditions for Phytophthora blight of vegetables. I know of at least one urban farm where this vegetable disease has been confirmed by the University of Maryland Plant Diagnostic Lab.
Vegetables in the squash family and the tomato/pepper/eggplant family are particularly prone to infection with Phytophthora blight. This disease is particularly destructive and difficult to manage.
What symptoms to watch for: Watch for suddenly wilting plants in wet fields or beds, with brown plant stems at the soil surface and soft, rotting fruit.
Image above: Phytophthora symptoms on pepper plant. Note wilted leaves and brown stem near base of plant. Photo by Don Ferrin, Louisiana State University Agricultural Center, Bugwood.orgImage above: Phytophthora symptoms on watermelon. Note soft “water-soaked” circular lesions on fruit, with white fungal-like growth. Photo by Jason Brock, University of Georgia, Bugwood.org
How to manage the disease
Confirm your diagnosis: If you suspect you have Phytophthora blight, seek help confirming the diagnosis.
Remove infected plants. Put them in the trash or bury them far from your growing area. Do not put in compost that will go back onto the farm.
Rotate crops. In a bed where you have had Phytophthora, avoid cucurbit crops and solanaceous crops for the next three years.
Chemical management can be used in conjunction with the above practices. Several fungicides are labeled for Phytophthora blight on vegetable crops. Consult the Mid-Atlantic Commercial Vegetable Recommendation Guidefor a list of products and application methods. Always read and follow the label prior to any pesticide applications.
Wyenandt, A., Vuuren, M. van, Kuhar, T., Hamilton, G., Hastings, P., VanGessel, M., & Johnson, G. (2020). Mid-Atlantic Commercial Vegetable Production Recommendations. https://njaes.rutgers.edu/pubs/publication.php?pid=e001
Most blueberry cultivars here in Maryland bloomed and green fruit are developing. Now is the time when a variety of pathogens and pest will begin to take up residence in your field which can harm your developing crop. It is important to perform routine scouting throughout your farm and make sure that you’re not seeing symptoms of some of
the common pests and pathogens. Below is a description of several of the most common diseases and pests you may find at this time in your blueberries.
Pathogens to be on the lookout for:
During the cool, wet days where temperatures do not reach above 70 degrees you may begin to see symptoms of several fungal pathogens including botryosphaeria canker or stem blight, botrytis, anthracnose and powdery mildew. These conditions make for an ideal environment for some of these fungal pathogens to grow or spread.
A.) Botryosphaeria stem blight, Bill Cline NCSU. B.) Botrytis, Caleb Slemmons, National Ecological Observatory Network. C.) Anthracnose, Bruce Watt, University of Maine D.) Powdery Mildew, Florida Dept. of Agriculture. Bugwood.org
Botryosphaeria stem blight (A) will exhibit dieback symptoms. It is initially detectable as yellowing and reddening of leaves which will move down then stem as vascular tissue becomes blocked by the pathogen. Whereas, botryosphaeria canker will develop as stem lesions which will sometime become swollen resulting in the formation of a canker. If botryosphaeria stem blight or canker is observed the best method to prevent the spread is pruning the infected tissue and fruit clusters six inches below any infected stems. Then, remove pruned branches from the field.
Botrytis (B) also known as gray mold, affectsboth fruit and the plant. It infects the fruit from bloom. Aswith botryosphaeria, the best tactic to reduce the spread of this disease is by pruning out infected fruit clusters and wood, then removing clippings from the field.
Anthracnose (C) will appear as stem, bud and leaf lesions and may have orange spore masses. Infections will cause leaf browning and will move from top of the leaf to the bottom. If untreated, anthracnose will also cause fruit rot. Fungicides may be used to prevent further development of anthracnose during the green fruit
development stage.
Powdery mildew (D) will start as chlorotic discoloration spots and develop into powdery masses on leaves. The infection usually begins in the spring with young leaves and may become more severe throughout the season eventually causing defoliation. However, while unsightly, powdery mildew will not significantly damage the developing fruit crop and therefore no action is required.
