Possible Changes to Atrazine Use

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By Kurt M. Vollmer, UME Extension Weed Management Specialist

The EPA is proposing several changes to its interim registration review decision for atrazine. The primary issue is the aquatic ecosystem level of concern (CE-LOC). The EPA had previously set this level at 15 ppb, but this was challenged in the Ninth Circuit Court of Appeals. Currently the EPA is proposing a much lower CE-LOC level of 3.4 ppb. This proposed level will have significant impacts on growers’ ability to use atrazine and other triazine products. Labels will also likely include new language to help mitigate the risk to aquatic plant communities. These include:

  • restricting atrazine applications when soils are saturated,
  • restricting atrazine applications during rain or storm events,
  • prohibiting aerial applications,
  • and reducing the annual atrazine application rate from 2.5 lbs. to 2 lbs. per acre annually.

Additional information can be found here: https://list.mg2.mlgnserv.com/track/click?u=df0ec74ed0bf23e091847f07c1d2c483&id=c31eec13d8967c36&e=d300d03f14fec2b3https://list.mg2.mlgnserv.com/track/click?u=df0ec74ed0bf23e091847f07c1d2c483&id=c31eec13d8967c36&e=d300d03f14fec2b3. The EPA is currently seeking public comments about the proposed decision (https://www.epa.gov/dockets/commenting-epa-dockets).

In addition the USDA Office of Pest Management Policy is conducting a related survey on atrazine usage practices for farmers involved in corn and sorghum production over the last three years (https://usdaopmp.gov1.qualtrics.com/jfe/form/SV_agW8JjsVXqR4jjg). 

New Risk Management Tools Online Training

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This summer, the University of Maryland (UMD) is partnering with the Maryland Department of Agriculture (MDA) and USDA to create a four-module online training course Maryland Farming Success.

The online training course is separated into four modules designed around preparing farmers for success by providing information about available USDA programs and creating the ability for participants to have a successful business plan, including – mission and goals, enterprise budgeting, risk management, and legal risk management.

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Corn Earworm numbers on the rise..

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Corn earworm moths counts in pheromone traps have been increasing over the past few days in some areas in Maryland and Delaware.  Sweet corn growers should keep an eye out and consider shortening spray intervals to a 2 to 3-day spray schedule while others could still be around a 3 to 4-day spray schedule.

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Unusual Disease of Garlic Scapes Found in Maryland

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Unusual Disease of Garlic Scapes Found in Maryland

By Jerry Brust, UME and Karen Rane, UMD Plant Diagnostic Lab

A grower noticed over the last few years lesions developing on their garlic scapes which then collapsed in the field. In previous years these collapsed scapes amounted to only a small number, but this year the losses are much greater approaching 30%. Symptoms consist of sunken lesions about ¼ to ½ inch long, that cause twisting, girdling and collapse of the scape. Lesions initially are cream to tan-colored but under rainy or very humid conditions, spore production by the fungus causes lesions to turn orange (fig 1). This disease is anthracnose of garlic, a new disease to Maryland and is caused by the fungus Colletotrichum fioriniae. The fungus may survive on crop residue in the soil from a previous garlic crop or the disease may be spread by infected bulbils used for propagation. Disease development is favored by rainy or very humid weather and warm temperatures (78-88o F). Anthracnose of garlic does not affect bulbs, but scape yield could be reduced as will bulbil production.

Fig. 1 Collapsed base of scape with white lesion and orange spores (left) and twisted orange scape stem (right). Photo by M.Mclearen.

Reports from New England indicate that onion is most likely not affected by this fungus. C. fioriniae has also been reported as causing bitter rot on pear and anthracnose on celery and cherry tomato. Crop rotation away from any member of the onion family may help reduce disease incidence. Besides crops, weeds such as common lambsquarters, redroot pigweed, yellow nutsedge and common groundsel may also be infected with the pathogen but be symptomless. Because this is such a new disease of garlic, fungicide recommendations have yet to be determined. However, products that are labeled and effective against purple blight of onion may be useful against this disease.

Blossom End Rot Common so Far this Season.

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Blossom End Rot Common so Far this Season.

By Jerry Brust, UME

This summer has been unusual as it has been about normal for temperatures if not a little cooler, but we have had greatly varying amounts of rainfall over the last month. Some areas have remained dry with storms just missing farms while others have been hit with some heavy rains. This can make watering vegetables challenging to avoid problems such as blossom end rot, which is caused by a calcium deficit in the developing fruit.

Figure 1. Fig 1. Several different vegetables with blossom end rot.

Calcium (Ca) moves to the plant via mass flow, i.e., where dissolved minerals like calcium move to the root in soil water that is flowing towards the roots. As it passes through the plant Ca is deposited in tiny amounts into the fruit. If anything slows or interrupts this stream the tiny amount of Ca needed at that moment is not deposited and the area furthest from the top of the fruit suffers—resulting in blossom end rot (BER). I have seen more BER this year on a large number of different vegetables than I have in the past several years (fig 1).

Figure two shows how precise and constant the Ca flow in a plant has to be to supply just the right amount of Ca at the right time. The large fruit on this particular plant developed before there was a Ca interruption, but the fruit a little younger suffered a Ca interruption, with the smallest (youngest) fruit suffering the greatest Ca interruption. At the time it was taken tissue analysis from this same plant showed that calcium was in the moderate range when the blossom end rot took place, demonstrating the importance of irrigation and water supply to reduce blossom end rot. Not much you can do about no rains or heavy rains, except try to maintain as even a water supply to your vegetables as is possible and remove any fruit from the plant you find that has blossom end rot.

Fig. 2 Older larger fruit received enough Ca, but younger (smaller) fruit did not so they are showing signs of blossom end rot.

 

 

 

 

 

Tomato Pith Necrosis in Maryland

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Tomato Pith Necrosis in Maryland

By Jerry Brust, UME

In the last week a few tomato fields in Maryland were found with the same disease called tomato pith necrosis. Just about all the problem tomatoes were from early planted fields. Tomato pith necrosis is caused by the soilborne bacterium Pseudomonas corrugata. Although in the past this disease occurred sporadically in Maryland, over the last few years it is appearing more frequently. Tomato pith necrosis usually is found in early planted tomatoes when night tempera­tures are cool, but the humidity is high, and often plants are growing too rapidly because of excessive nitrogen application. We have had a spring/early summer with some cool nights and high humidity.

Fig. 1. Beginning of pith necrosis- leaves anywhere on plant can turn yellow. Photo by G.Brust, UMD

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Tomato Spotted Wilt Virus in Tomatoes

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Tomato Spotted Wilt Virus in Tomatoes

By Jerry Brust, UME

A few high tunnels and even a couple of tomato fields have been found with tomato spotted wilt virus (TSWV) in Maryland. The high tunnel finds were not too surprising

but the fields were, as we usually do not see field infections until much later into the season. TSWV has also been found in greenhouse and field production of cut flowers. So it appears this virus is more common this year than it usually is, most probably due to greater thrips populations being present in our greenhouse production areas.

Fig. 1 Tomato leaves with TSWV symptoms

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2022 Strawberry Twilight Meeting

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2022 Strawberry Twilight Meeting
Wednesday May 25, 20222. 6:00PM – 8:00PM
University of Maryland Wye Research and Education Center
211 Farm Lane, Queenstown, MD 21658

Come and listen to University and USDA Specialists discuss current conditions and issues with Maryland strawberry production, including fungicide resistance and scheduling fungicide sprays. Also, come meet the new farm manager, Chris Cochran and check out other information on other berry crops at WREC.

Photo by E. Rembery

See and taste some of the varieties in the 2021/22 annual plasticulture variety trial, which includes a few standard varieties, as well as a few newer available selections.

As always, a sweet treat will be served at the conclusion of the program.

To register, please fill out the registration form.
This program is free, but we ask that you please RSVP for planning purposes.

Grower suggestions welcome!
For more program information, contact Chris Cochran at 410-827-7388, ccochra3@umd.edu

May Vegetable Insect Scouting Update

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 May Vegetable Insect Scouting Update

By Emily Zobel
Ag Agent Dorchester County

It is crucial to check 5-10 locations (50+ plants) throughout the field when making treatment decisions. Localized infestations can be spot treated to save resources, time, and money. For up-to-date chemical recommendations, check the Mid-Atlantic Commercial Vegetable Production Guide or consult your local extension agent.

Spotted Lanternfly Update! 

Spotted lanternfly eggs are hatching. Be on the alert when moving equipment or plants out of the quarantine areas. Early instar nymphs are black with domino-like white spots.

Asparagus: Continue to scout for asparagus beetles. Feeding by beetles can disfigure spears, and depending on the market, the presence of eggs on the spears can make them unmarketable. When scouting, count adults, eggs, and larvae, and take note of the damage to each plant. Consider treatment if >10% of the spears are infested with beetles (1 or more per plant) or 1-2% have eggs or damage. Treat ferns if 50-75% are infested.  Minimize the impact of spear damage on asparagus fields by harvesting asparagus spears every day during the harvest season.

 Brassica/Cole crops: Recently transplanted and newly emerged seedlings of cole crops are at risk of damage from flea beetles. Scout early and consider treating when 50% or more plants show injury and flea beetles are present on plants. Scout fields for imported cabbageworm (ICW) (Fig 2.)and diamondback larvae. With warmer temperatures on the way, these infestations can increase rapidly. When scouting, paying particular attention to the innermost leaves where ICW often feed, consider treating for fresh market cabbage, broccoli and cauliflower if caterpillars are found on 20% or more plants during the seedling stage. Infestations up to 30% may be tolerated from early growth to cupping. On cabbage, once heads begin to form, a 5% threshold should be observed to protect the marketable portion of the plant. For broccoli and cauliflower, use 15% at curd initiation/cupping and 5% from curd development to harvest. For leafy greens such as collards and kale, 10% plants infested is the threshold throughout the season.

Melons: As the weather warms up, you will want to start scouting melons for aphids, cucumber beetles, and spider mites since once we get a few consecutive days of warm, sunny weather, populations can explode. Consider treating if an average of 2 adult beetle is found per plant. For spider mites, treatment is warranted when 10-15% of the crown leaves are infested early in the season and when 50% of crown leaves are infested late in the season. The continued use of Sevin or the pyrethroids may result in mite outbreaks.

Sweet Corn: Sample for cutworms and flea beetles. As a general guideline, treatments should be applied if you find 3% cut plants or 10% leaf feeding. In order to get an accurate estimate of flea beetle populations, fields should be scouted mid-day when beetles are active.

Who has Been in My Strawberries? Slugs and Sap Beetles, Two Common Insect Pests on Strawberries.

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By Sankara Ganesh, Maria Cramer, and Kelly Hamby.
Department of Entomology, University of Maryland, College Park

The cool, wet spring weather we have been experiencing favors slugs, so be on the lookout for slug damage. Slug damage may easily be confused for sap beetle feeding, but management of these pests is very different, so it is important to correctly identify the problem. Both pests can be common in matted row production.

Damage: Slug feeding renders fruit unmarketable and susceptible to infestation by other pests including sap beetles. Sap beetle adults are attracted to ripening, ripe, and overripe fruit and directly cause damage through feeding, but may also introduce pathogens and contaminate fruit with larvae. Sap beetles tend to leave behind circular holes while slug damage is often irregularly shaped, and both can cause moderate to deep holes. However, slugs will also feed on leaves and leave behind slime trails.  Monitoring is important to conclusively determine which pest is causing damage.

Figure 1. 1A) Slug feeding on unripe strawberry (K. Hamby). 1B) Slug feeding damage (M. Cramer).
Figure 2. 2A) Sap beetle feeding on strawberry (K. Hamby) 2B. Sap beetle feeding damage (N. Hummel, LSU)

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