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Pumpkins are one of our favorite fall decorations, food sources, and animal feed sources in Delaware.
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Pumpkins are one of our favorite fall decorations, food sources, and animal feed sources inpumpkin-fruit-rot Delaware. Agro-tourism, including fall hayrides, pumpkin picking, and other activities are strong sources of farm income. Fruit rots caused by fungi and bacteria can diminish profits of farmers, especially in seasons with wet weather, high humidity and fluctuating temperatures.  Fruit rots also disappoint consumers who expect a purchased pumpkin to last a long time. Micro organisms can cause problems during storage post-harvest.  Avoid wounding pumpkins at harvest, during transit, and keep in a cool location. Wounds allow micro organisms to enter.
The fungus-like organism Phytophthora capsici has a very wide host range, including cucurbits such as pumpkin, watermelon, squash, and tomatoes, beans, and other vegetables. If a pumpkin develops a white powdery soft rot such as in the picture, it may be due to Phytophthora. Discard it in the trash, do not compost in gardens or use the seeds to start plants for next season. Phytophthora is not harmful to humans or animals, but secondary fungi can move in. The black specks in the picture show some secondary fungi that have started to grow on the affected area.
N Gregory 10/21/2016

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Click for New Updated Fact Sheet on Boxwood Blight DE fact sheet Sept 2016
Boxwood Blight Leaf
The fungus Calonectria pseudonaviculata (Cylindrocladium pseudonaviculatum) causes severe defoliation and death of container grown boxwoods, and dieback in older plantings. Most boxwood species are susceptible, including American and English boxwood (Buxus sempervirens), little leaf boxwood (B. microphylla) and hybrids such as B. sinica. Pachysandra is a host, and can be a source of spores capable of causing new infections. Sweetbox (Sarcococca) has recently been identified as a host. There are a number of other diseases that affect boxwood, and environmental stress plays a role in susceptibility and predisposition to disease. Timely and accurate identification by microscopy is important for management of this aggressive disease...
NFG 9/20/16

BLS has been very damaging to red oaks in Delaware and the Mid-Atlantic states since the early 1990’s
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BACTERIAL LEAF SCORCH (BLS) of hardwood trees, shrubs, and herbaceous plants, is caused by the bacterium, Xylella fastidiosa, carried by small insects such as leaf hoppers and sharpshooters. BLS has been very damaging to red oaks in Delaware and the Mid-Atlantic states since the early 1990’s. Northern red oak and pin oaks under environmental stress are more susceptible. Symptoms include marginal discoloration or scorch of leaves in late summer or early fall, often with a yellow or dark band on the inside edge of the discolored area. Symptoms are similar to those caused by drought or root issues that interfere with flow of water and nutrients. Plants may not develop symptoms for a year or two after infection, but then thinning of branches occurs and trees die within 5 to 8 years.  Infection is confirmed with a lab test for a fee, so if confirmation is needed, please arrange to have samples tested by contacting the UDBLS Red Oak 2016 Plant Diagnostic Clinic. Please note that there is a $20 fee for BLS testing. To manage, maintain good tree vigor, and remove infected trees. A UD fact sheet has more info: http://extension.udel.edu/factsheets/bacterial-leaf-scorch/
NFG 8/30/2016

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CHICKEN OF THE WOODS or the sulphur shelf fungus (Laetiporus Laetiporus sulphureus Newark DE 2016sulphureus) has been seen at the base of trees with large bright yellow and orange overlapping fruiting structures. These fungi are some of the most colorful and identifiable fungi found on living or dead trees. Chicken of the woods is a choice edible, but must be positively identified by an expert. It is one of many fungal species that attack the heartwood of trees, and produce fruiting bodies on the trunk. Laetiporus is common in oak trees, as many of these Basidiomycetes are found in association with certain trees. If one tree has heart rot, it doesn't mean that nearby trees will get it, even if they are of the same species. The fungus must enter through a wound in order to become established, and the fungus will slowly decompose the heartwood, the dead wood or center of the tree. By the time a fruiting body is produced on the trunk of a living tree, it usually means that the fungus has been there for years. At this point there is no control but to keep tree stress low. Rotting of the interior wood can weaken the tree, leading to breakage, insect damage, and other diseases. An arborist may be able to prune to save the tree.
NFG 8/21/16

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After a cool and rainy start to the season in Delaware, it has turned hot and dry. Rains have come in downpours, most of which runs off.
Keep an eye on trees and shrubs, as well as annuals, perennials, and vegetables. Newly planted trees and shrubs may take up to two or three years to become established in the landscape. Water once or twice a week, deeply, if there is no rain. Watering deeply means to apply about the equivalent of one inch of rain. A soaker hose can be run about 45 minutes, or a sprinkler about the same, depending on water output. Do not water daily. Water early in the day, so that foliage has time to dry. Foliage can be scorched by the sun and water droplets magnify the sun's rays. If foliage is wet overnight, disease can set in. Don't fertilize newly established trees and shrubs that are putting out small feeder roots, as salts can damage those new roots. Wait until fall to apply fertilizer to lawns and wait until spring to apply fertilizer to shrubs and trees.

Establishment of new trees takes time
Establishment of new trees takes time

NFG 8/12/2016

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Pest and Beneficial Insect Walk 2016    Wednesday, June 22, 2016, 4 - 6 PM Credits: 2 Pest., 1 CNP.  UD Botanic Gardens,  University of Delaware Campus, Townsend Hall, 531 S. College Ave, Newark, DE. Learn to identify insect and disease pests, as well as beneficial insects in the landscape.  Instructors: Nancy Gregory, Brian Kunkel, and Carrie Murphy. Meet by the Fischer Greenhouse.Disease and Insect Workshop_2015
Disease and Insect Identification Workshop 2016    July 13, 2016, 4-6 PM Credits: 2 Pest., 1 CNP. Townsend Hall, 531 S. College Avenue, Newark, DE. Learn about signs and symptoms the Cooperative Extension staff look for to identify pests and diseases! Tips and techniques will be shared for fresh and preserved plant samples, and use of hand lenses and microscopes will be taught. Bring your own samples to look at!  Instructors: Nancy Gregory, Brian Kunkel, and Carrie Murphy
NFG June 2016

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Photo Credit: Michele Walfred
Hydrangea Frost Damage Photo Credit: Michele Walfred

Cloudy, wet, damp, cool and dreary are words that have been heard over and over recently, regarding the weather in Delaware. Cloudy and damp weather is conducive to plant pathogens that infect in the spring. Fungi and bacteria overwinter in twigs and buds of trees and shrubs. Spring rains and humidity will prompt new growth and spore production, and then winds and rains carry spores to newly emerging flowers and leaves. Recent weather has favored plant disease, but we have also had injury from freezing weather that occurred in April.  Hydrangea has been reported with browning and dieback, and samples have come into the Plant Diagnostic Clinic. New growth came out early due to warm weather, and growth of buds and leaves has been affected by the freezes that we had in the area April 5, 6, and 10th. Plants will put out new growth when the weather warms again. Affected growth could be pruned back, depending on the type of
Boxwood Frost Damage 2016 Image, N. Gregory
Boxwood Frost Damage 2016 Image, N. Gregory

hydrangea, and whether it blooms on new wood or old. Frost or freeze damage has also been observed on new growth of boxwood, and other shrubs. These plants should put out new growth when the weather warms. Fruit trees that were affected by frost and freeze will have fewer fruits this season. Keep up fruit tree sprays. Fungicide sprays should also be going on Douglas fir and spruce that are affected by needlecast fungi. Fungicide applications should be made when new needles are ¼ inch long, followed by a second application ten days later. Check annuals carefully for Botrytis blight or grey mold, and prune or discard plants. Sanitation is a big part of plant disease management.
N. Gregory 5/6/16

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A new UD Cooperative Extension fact sheet lists sanitizing products available for use in greenhouse, nursery, and landscape uses. These products can be used to clean and reduce microbial populations on  pots, tools and surfaces.  Products, trade names, usage guidelines, and cautions are listed in an easy to read format at this link:  Sanitizing Products for Greenhouse Nursery and Landscape for Delaware
NFG 4/8/16

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Penn State University has distributed information from fruit specialist Jim Schupp regarding how to asses fruit tree health following the recent freezing weather:  Peach Bud Survival - Compare the number of live buds to the number a fruiting lateral should carry based on the target yield per acreimage014

  1. To get a good estimate, examine about 150 to 200 flower buds per variety per block.
  2. Collect one strong fruiting lateral (pencil thick and 24 to 32 inches long) from each of two sides of 5 representative trees per block.
  3. Bring the fruiting laterals into a heated building, place them in buckets of water, and allow them to warm up.
  4. Count and record the total number of flowers and unopened buds on a branch.
  5. Examine the ovule in the center of each flower, and count the number that are healthy.
  6. Compare this number per fruiting lateral to your desired crop load. If, for example, you have 12 live flower buds on a fruiting lateral that should carry 3 peaches at harvest, then you have four times as many live flower buds as are required for a full crop.

More info can be found at:  http://extension.psu.edu/plants/tree-fruit/news/2014/grab-some-buds
NFG 4/7/2016

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Bradford PearBradford pear trees are blooming now in Mid-Atlantic landscapes. Also called callery pear, with some selected cultivars such as Cleveland Select, the flowering pear trees native to China are weak in branch structure. These V-shaped trees usually split or lose branches after 15 to 20 years of growth. Thought to be sterile and not produce fruit (just flowers) the callery pears cross pollinate with other pear trees in the landscape, and some do produce fruit. The fruit are small and inedible, but are eaten and carried by birds, ultimately settling and seeding in areas such as roadside ditches and easements.  Roadsides are populated with many volunteer flowering pears, more numerous and invasive over time. Some have thorns.  There are many other small flowering trees that are more suitable for planting. Consider native trees, such as fringe tree, serviceberry, or redbud. Callery pear, Bradford pear, or any of the selections from those, are not good options.  See the Plant Invaders of Mid-Atlantic Natural Areas and the associated web site of the National Park Service:  https://www.nps.gov/plants/alien/pubs/midatlantic/pyca.htm
NFG 3/30/16