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June 13, 2022

Native White Birches & Their Resistance to the Bronze Birch Borer

The Dilemma Regarding Birch Trees

Bronze birch borer adult female laying an egg on the bark surface of a birch tree. (Photo Credit: Ohio State Coop. Ext.)

Bronze Birch Borer (Agrilus anxius) adults (440-800 GDD) are now actively searching landscapes for various species of Betula (Birch) to lay eggs upon. The adult beetles will be attracted to susceptible trees that are genetically defenseless or are compromised from stress (e.g., especially drought stress).

It is well known that the native River Birch (Betula nigra) has a strong resistance against the BBB. As a result, this species has been extensively planted in NJ landscapes during the past few decades to the extent of arguably being over-planted. And it is also widely understood that the non-native Asian & European birch species have virtually no or little resistance to the BBB. Therefore, the planting of these non-natives has rightfully been reduced over the decades. However, what about some of our other native species such as the paper, gray, & yellow birches. Is it best to avoid planting these species as well?       

River birch (Betula nigra) is a native birch that is strongly resistant to the bronze birch borer. (Photo Credit: Steven K. Rettke, Rutgers Coop.Ext.)

Is it best to avoid planting other native birch trees in our landscapes, such as the gray birch shown above? (Photo Credit: Steven K. Rettke, Rutgers Coop. Ext.)

 

 

 

 

 

 

 

 

 

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Filed Under: Landscape, Nursery, & Turf, Nursery, Plant Diagnostic Lab
June 8, 2022

Crop Progress and Hessian Fly Sightings

Hessian Fly From Dough Stage Wheat

June 8, 2022 Salem County, NJ

Salem County has experienced nearly two weeks of ideal temperatures in the mid 80’s to low 90’s allowing for a considerable amount of soybean acreage to be planted, and hay acreage harvested. Rye for grain harvest is nearly complete and barley will soon follow. With a 72-hour forecast of one inch to one and a half inch expected, many producers have switched back to planting as the window to make dry hay closes.

Corn: Early planted corn is near canopy and in very good condition. Surface moisture is adequate but at this stage of rapid stem elongation, rain is needed to replenish the two inches of rain received at the end of May but less than a tenth of an inch in the last week. Overall, most of Salem County received in excess of 12 inches of rain in the last 90 days ending June 6, which is over an inch and a half more than the average for this period of the growing season and substantially more than the drought stressed crops in Cape May County that are experiencing a 75% deficit in moisture for the last seven days. Corn planted into standing rye and other late terminated cover crops is lagging behind tilled fields due to moisture competition and carbon sink, but overall flushes of seedling broadleaves are not present indicating preemergence programs are working effectively.

Soybeans: Full season soybean planting is nearly complete. Emerged beans are ahead of seedling flushes of pigweeds but behind giant ragweed in areas where ragweed is present. Expect amaranth species weed pressure to increase significantly after this weekend’s forecasted rain.

Wheat:  Wheat is drying down rapidly and in overall good to excellent condition. In areas where irrigated wheat is already yellow and evidence of wind damage is visible, Hessian Fly is the most likely culprit as seen in this photograph taken in a dough stage field. Flowering canada thistle seen in wheat that will be double cropped with soybeans should be de-headed to prevent seed dispersal prior to harvesting. In enlarging patches, consider a spot-treatment (sacrificing soybean) of a growth regulator herbicide if prior treatments of glyphosate products have not limited spread. 

About Hessian Fly: Mayetiola destructor (Say) is a grain pest in the Cecidomyiidae family. It is a major cause of wheat yield reduction around the world. The fly forms galls on the underside of wheat leaves that protect the feeding larva from efficacious applications of insecticides. In addition to wheat, Hessian fly can be found in rye, barley and in brome grasses (and reedscanary). Bromes are a major composition of the grasses in this area. Egg hatched occurred when temperatures were above 50 degrees earlier this season.

Seven Day Precipitation Departure From Normal

https://www.weather.gov/marfc/Precipitation_Departures

If producer’s noticed patches of dark green areas of wheat (barley) in the same fields now infested with flies or where lodging is increasingly evident, these are an indicator of where the larva were pupating.

Larval feeding after stem elongation causes lodging. Feeding damage can also cause failure to produce a seed head, and a reduce seeds per spike and light test weight. – Journal of Integrated Pest Management, September 2018 article.

The adult swarm seen today are emerging after fourteen days of ideal weather above 70 degrees Fahrenheit. Now that flies are present, they will lay eggs over the course of the next week.

 

Due to climate change, it is possible that there could be three emergences of Hessian Fly this year. Southern states see as many as six generations. Generally, in northern states past recommendations have suggested the fly has an emergence in the spring and again in the fall. But in southern states emergences occur in multiples of one, two three in spring, and again in fall. Which is where management strategies come into play. Knowing the number of emergences in our area can help producers calculate if delayed planting will assist with controlling a two brood a year emergence or if it is unlikely to help with multiples of brood emergences. Wind plays a major role in dispersal from infected fields to non-infected fields. Due to cover crop program planting dates for small grains, producers with Hessian Fly issues should talk to their local NRCS office to make sure program planting dates take into account the local Hessian Fly Free dates for fall of 2022.

What to do now: Producers can identify Hessian Fly by looking for swirling clouds of insects that look like white smoke coming out of the wheat canopy. Swatting the swarm will trap flies on the palm of the hand for easier identification. The female fly has a distinctive orange striping to her abdomen. Hessian flies are orange and black banded compared to the overall all orange appearance of wheat midges.  At this stage, the flies have already pupated through the larval stage, which already damaged the wheat crop by tunneling into the stems. Most likely lodging is evident nearby.

What producers can do to plan for next year: Hessian fly was most likely introduced to North America in infected straw bedding. Straw from infested fields may still contain larva. The fly and larva are not considered a pest of stored grain. The larva pupate in the axis of the leaf stem. Cutting straw stubble below the leaf nodes and removing it from the field may help in management as the Hessian Fly larva overwinter inside a flax-seed like cocoon (puparia) at the base of infected plants. Plant resistant cultivars, delay planting dates if this year’s infestation is associated with an earlier planting date, destroy volunteer wheat, and manage brome grasses in field edges and within field when possible.

Hessian Fly Free Planting Dates in Southern New Jersey: “In Maryland, plant wheat following the Hessian fly-free date for your area. This date is approximately September 30 for the Hagerstown area and becomes progressively later as you move from the south and east in the state. The fly-free date is October 13 on the Lower Eastern Shore.” – Read more in 10 STEPS TO PROFITABLE WHEAT PRODUCTION in the Maryland Agronomy News.

Additional considerations for producers planting winter wheat – double crop soybeans-winterwheat: “Growers should avoid planting wheat into last season’s wheat stubble. Continuous no-tillage, wheat-double-cropped-soybeans may result in severe problems and should be avoided in Hessian fly problem areas.” – https://www.farmprogress.com/grains/hessian-fly-resistance-threat-southeast-wheat

Source information. For a detailed publication on Hessian Fly (Diptera: Cecidomyiidae) Biology and Management in Wheat visit Journal of Integrated Pest Management, (2018) 9(1): 14; 1–12 issue.

Salem County Producers, if you are seeing signs of Hessian Fly lodging, contact Melissa Bravo at the Salem County Extension Office so fields can be monitored in the fall to determine the Hessian Fly Free dates for this area. 

Filed Under: Field, Forage & Livestock, Landscape, Nursery, & Turf, Uncategorized, Vegetable Crops
June 7, 2022

Questioning the Plant Stress Hypothesis

Definition

The Plant Stress Hypothesis generally states that plants subjected to stressful conditions become more susceptible to attack by insects and diseases. This is often thought to be due to the plant’s increased suitability as a food or due to the reduced ability of the stressed plant to defend itself. It is commonly believed that when a plant is stressed it becomes better food for “bugs.” Is it correct to state that plant stress leads to pest outbreaks, or is the statement too simplistic?

The Experiments

A publication written in 1998 (Koricheva et. al.) summarized approximately 70 controlled experiments that were performed to study how distinct types of plant stresses affected insect/mite attacks. Diverse types of environmental stresses were included in these studies (e.g., drought stress, waterlogged roots, ozone exposure, excess shade, as well as many others). Plant nutrient stress & insect impacts has been researched but was not performed within these studies.

Plant roots stressed from waterlogged soils were included in these studies. Research also included other types of environmental stresses such as excess shade & ozone exposure. (Photo Credit: Steven K. Rettke, Rutgers Coop. Ext.)

Dogwood leaves scorched from environmental drought stress. How does this plant stress impact insect herbivores? (Photo Credit: Steven K. Rettke, Rutgers Coop. Ext.)

 

 

 

 

 

 

 

 

 

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Filed Under: Landscape, Nursery, & Turf, Nursery, Plant Diagnostic Lab
June 1, 2022

Bagworm hatch & Boxwood Blight potential now through Friday

Boxwood Blight (BWB) Alert – Infection Potential (Now – FRIDAY) 

There is a potential for new boxwood blight infections throughout much of NJ. The end of week rains coupled with more mild temperatures, cloud cover, and prolonged periods of leaf wetness will contribute to the spread or worsening of boxwood blight infections.

Boxwood Blight Risk Assessment as of 5/24/2022
Region Location CODE 1-June 2-June 3-June 4-June 5-June 6-June
Southern Upper Deerfield NJ50 Very Low  Infection Risk Infection Risk Very Low Very Low  Very Low 
Central Howell / Freehold NJ10 Infection Risk Infection Risk Infection Risk Very Low  Very Low  Very Low 
Northern High Point NJ59 Infection Risk Infection Risk Infection Risk Very Low  Very Low  Very Low 
Check local boxwood blight risk here (CLICK HERE – input your area code – select closest weather station – check 7-14 prediction – click on graph / table)

 

ALSO: Volutella Blight is extremely common and readily mis-diagnosed as boxwood blight or vise-versa.

  • There is a free / open to the public seminar June 23, 2022 about this important disease. Boxwood International Seminar on Biology and Management of Boxwood Volutella Blight by Prof. Tom Hsiang, University of Guelph, Guelph, Ontario, Canada. Registration Link: Click here to register

Pest Scouting – Please refer to these documents for a full listing of insects pests for your area corresponding to growing degree-days (GDDs). 

Bagworm hatch is upon us in Southern NJ and will soon be /already the case throughout NJ. Please be ready to control these insects during the VERY SHORT treatment window.

Days old bagworm size.  Bagworm female case with developing juveniles

BAGWORMS (600-900 GDD) (Bagworm hatch prediction as of 6/1/22)
Crop type Common Name Scientific Name GDD Min (50F) GDD Max (95F) Reference Developmental / Target Stage
Conifer mostly, many minor hosts Bagworm Thyridopteryx ephemeraeformis 600 900 RU Larvae (early instars) – ONLY CONTROL WINDOW
Region Location Station Date (600 GDD) Date (900 GDD) Treatment window  Bagworm Hatch – Predictions only, SCOUTING is critical! Treat as soon as larvae detected. 
South Upper Deerfield NJ50 30-May 12-Jun 13 days
Central Howell / Freehold NJ10 3-Jun 18-Jun 15 days
North High Point NJ59 14-Jun 30-Jun 16 days 

 

Filed Under: Landscape, Nursery, & Turf, Nursery, Turf Tagged With: , , , , , , , , ,
May 24, 2022

Nursery Pests Scouting June – Bagworms, Scales, Borers, RHFB, BWB

Red-headed flea beetle – Adult emergence beginning any day now

Please refer to this timeline of pest development compiled by Tim Waller in communication with Brain Kunkel (Unv. Del) and Danny Lauderdale (NC State)

  • Contains material selection and timing, along with regime information and considerations

Boxwood Blight Alert – Infection Potential (Saturday) 5/27

Boxwood Blight Risk Assessment as of 5/24/2022
Region Location CODE 24-May 25-May 26-May 27-May 28-May 29-May
Southern Upper Deerfield NJ50 Very Low  Very Low  Low  High Risk Very Low  Very Low 
Central Howell / Freehold NJ10 Very Low  Very Low  Low  Infection Risk Very Low  Very Low 
Northern High Point NJ59 Very Low  Very Low  Very Low  Infection Risk Very Low  Low 
Check local boxwood blight risk here (CLICK HERE – input your area code – select closest weather station – check 7-14 prediction – click on graph / table)

 

Refer to the most recent Alert for more information – CLICK HERE

Pest Scouting – Please refer to these documents for a full listing of insects pests for your area corresponding to growing degree-days (GDDs). 

Contact if seeing insects at different times: twaller@njaes.rutgers.edu (or call the Cumberland County Extension Office – 856-451-2800)

The following key groups of pests will be active, vulnerable, or otherwise treatable during the next month throughout most of NJ. Here, bagworms, scale insects and borers with key life stage events during the 350-1500 GDD timeframe are discussed. Note there are many other insect pests present this time of year so please view the pest scouting guides above for your particular needs.

Projected GDD50 accumulation as of 5/24/2022 (USPEST) Note: Growing degree-day values utilize daily average air temperatures with a minimum temperature threshold (a.k.a. ‘base’) of 50F = GDD50 (max. temp. threshold set at 95F). These values are accumulated from a biofix date, such as January or March 1st in the NE USA. Provided GDD50 are scouting ranges and should be truthed.
Region Location Station 24-May 1-Jun 1-Jul
South Upper Deerfield NJ50 488 638 1358
Central Howell / Freehold NJ10 426 551 1203
North High Point NJ59 288 387 909
Forecast: NOAA NCEP Coupled Forecast System model version 2 (CFSv2) forecast system (3.5 months) (USPEST.ORG)

Refer to this post “Obtaining your local growing degree-days” for additional information 

BAGWORMS (600-900 GDD) (Bagworm hatch prediction as of 5/24/22 – now until July 14 (Southern NJ (NJ50)))
Crop type Common Name Scientific Name GDD Min (50F) GDD Max (95F) Reference Developmental / Target Stage
Conifer mostly, many minor hosts Bagworm Thyridopteryx ephemeraeformis 600 900 RU Larvae (early instars) –

ONLY CONTROL WINDOW

Refer to this post for additional information on Bagworms

BORER Insect Activity for 350 – 1500 GDD (Now until ~July 1 in Southern NJ (NJ50))
Crop type Common Name Scientific Name GDD Min (50F) GDD Max (95F) Reference Developmental / Target Stage
Malus, Prunus, many Lesser peach tree borer Synanthedon pictipes 350 375 4 Adult flight, egg laying
Dogwood, apple, pecan, elm, hickory, willow Dogwood borer Synanthedon scitula 350 850 4 adults, eggs, caterpillars
Birch Bronze Birch Borer Agrilus anxius 440 880 RU Adults (egg laying)
Malus, Prunus, many Peach Tree Borer Synanthedon sp. 500 600 RU Adults – emerge (1st treatment both types)
Rhododendron Rhododendron borer Synanthedon rhododendri 509 696 RU Adults emerge
Malus, Prunus, many Greater peach tree borer Synanthedon exitiosa 575 710 4 Adult emergence
Many Roundheaded appletree borer Saperda candida 802 1129 RU Adults
Ash Emerald ash borer Agrilus planipennis 1000 1200 4 Peak adult activity
Malus, Prunus, many Peachtree borer Synanthedon sp. 1500 1800 RU Larvae Treatment
Many Roundheaded apple tree borer Saperda candida 1514 1798 5 Typical treatment window
Conifer Nantucket tip moth Rhyacionia frustrana 1514 1917 RU Adults 2nd generation

Click here – “Identifying Clearwing Moth Borers in Pheromone Traps” or “Differentiating the Common Wood Borers of Ash Trees”

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Filed Under: Landscape, Nursery, & Turf, Nursery, Turf Tagged With: , , , , , , , , , , , , , , ,
May 17, 2022

Leaf Spot and Melting Out……of Pachysandra?

Last week’s post concerning leaf spot diseases in turfgrass, and a few samples of dead pachysandra in the lab this week, got me thinking about how much I hate pachysandra. Hate might be too strong a word for a plant, but like Neumann and Jerry, this subshrub is my nemesis. Some of you may have heard me tell stories about trying to rid my home garden of pachysandra and finding it impossible to kill, but subsequently planting several hundred plants at my late-mother’s house only to see them all die of disease, so surely you can empathize with my perspective!

Pachysandra can grow in deep-shade areas, so it is well-suited and popular as a ground cover for shade gardens. The most commonly used species is P. terminalis, the Japanese spurge, which is an aggressively spreading evergreen. It is very deer-resistant, which unfortunately, also means that it gets planted into many New Jersey landscapes and gardens for that reason alone.

Deep shade usually means a wet site and that is where the disease issue comes in. Pachysandra, especially P. terminalis, is susceptible to the fungus Pseudonectria pachysandricola, which is the cause of the disease Volutella Leaf and Stem Blight. Leaf and stem blight is the most destructive disease of pachysandra in New Jersey.

Photo 1: Leaf spot phase of Volutella Leaf and Stem Blight. Photo: Richard Buckley, Rutgers PDL

Numerous patches of wilting and dying plants in a landscape bed are often the first indication that Volutella blight is in active in the bed. Both leaves and stems are attacked by the causal fungus. Leaves develop irregular tan to brown blotches, often with concentric circles of light and darker zones and sometimes with dark-brown margins. These blotches gradually increase in size until the entire leaf turns brown or black and dies. Stem cankers usually develop and cause whole plants to die back. Stem cankers can appear at any point on the stem and begin as greenish-brown and water-soaked lesions that eventually turn brown or black as the stems shrivel. As the fungus girdles the stem, sizeable parts of the plant beyond or above that point turn brown and die. Plant death from stem infections can be quite extensive, so the planting appears to melt away in a manner very much like turfgrass subjected to leaf spot and melting out.

Photo 2: Stem infection of Volutella Leaf and Stem Blight. Photo: Sabrina Tirpak, Rutgers PDL

Photo 3: Melting out of a Pachysandra planting due to Volutella Leaf and Stem Blight. Photo: Richard Buckley, Rutgers PDL

During wet, humid weather, affected plant parts can be covered with reddish-orange, cushion-like fungal fruiting bodies, called sporodochia. Conidia (asexual spores) produced in the sporodochia disseminate the fungus within the planting. They are easily spread by rain splashing and wind, or mechanically by people working the bed during wet weather. If blight is suspected, but fruiting bodies are not evident, place suspect plant material in a plastic bag with a moist paper towel. In a day or two fruiting bodies will develop that can be seen with a hand-lens.

Weak or injured plant material is much more susceptible to the disease than healthy tissue, so damage may be very severe when plants have been stressed by excessive sunlight, winter injury, drought, or insect attack. Spread of the fungus is also more rapid in dense plantings, where heavy mulches are used, or in beds with residual leaf debris. Planting beds subject to regular overhead irrigation often have more disease activity.

Photo 4: Winter injury to Pachysandra. Photo: Dr. Ann Gould, NJAES

Photo 5: Euonymus scale on Pachysandra. Photo: Richard Buckley, Rutgers PDL

Normally this disease does little damage to vigorous plants, thus providing good growing conditions is one of the most important control measures. Begin by selecting healthy, disease-free planting materials. Plant in a well-drained soil and on sites with suitable sun/shade exposure.

Control of the disease in an infected planting bed begins with good sanitation. Remove and destroy all of the affected plants and plant debris. Use a regular lawn mower set at a 1 to- 2 inch cutting height to mow the affected area. Catch all of the debris in a bag and discard. Be sure to mow an area well outside of the diseased patch. A little nitrogen fertilizer will help the remaining plants to fill in the mowed area.

Prune trees and shrubs to increase light penetration and air circulation in and around the site to help keep it dry. Avoid overhead irrigation and avoid wet foliage whenever possible. If irrigation is needed to avoid drought stress, then water early in the day, so the foliage can dry as quickly as possible.

On high value landscapes, and after sanitation and moisture management issues are corrected, fungicides may be an effective addition to a management program: make applications of chlorothalonil, copper, mancozeb, myclobutanil, or thiophanate-methyl at the first sign of disease and repeat at label specified intervals and rates.

I’ll leave you with this existential question: are you sure you really want to plant pachysandra? How about a hosta or something instead?

Filed Under: Landscape, Nursery, & Turf, Nursery, Plant Diagnostic Lab, Turf