Dear Wisconsin nurseries, Christmas tree growers, and gardeners:

After a cool, slow start to the spring, with the hot temperatures this week, plants, pests and diseases are finally starting to pop. Read up on what we've been finding below.

Please send any feedback, questions, or ideas for future e-news updates to datcpnursery@wisconsin.gov.

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^{A calibrachoa showing leaf mottling caused by CPMMoV | DATCP image}

Pathogen Highlight: Chili Pepper Mild Mottle Virus

Chili pepper mild mottle virus (CPMMoV) is a newly detected tobamovirus infecting calibrachoas this year. The entire host range of this virus is not yet know. Other plants may be susceptible to CPMMoV, especially other solanaceous species, including tomato and pepper. 

Symptoms of CPMMoV include leaf mottling, flower break, necrotic lesions, and general stunting.

Similar to tobacco mosaic virus (TMV), CPMMoV is highly transmissible by touch, so wear gloves and avoid touching potentially infected plants with hands or tools. If plants suspected of being positive need to be touched for testing or disposal, gloves should be worn. After touching plants, dispose of gloves and sanitize any tools, benches, door knobs, that may have come in contact with potentially infected material using a 10% bleach solution.

If you suspect your plants may be infected and are a licensed nursery grower or dealer, contact DATCP’s Nursery Program at (608) 224-4572 or datcpnursery@wisconsin.gov. If you are a homeowner, contact the UW-Madison Plant Disease Diagnostic Clinic https://pddc.wisc.edu/.

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^{Honey bee foraging on salvia | DATCP T. Boyle}

Celebrate World Bee Day - May 20, 2022

May 20 is World Bee Day and we can all celebrate it -- learn more here. DATCP supports Wisconsin beekeepers, honey bees, and wild pollinators through our Apiary Program services.

The DATCP Apiary Program offers free inspections to Wisconsin beekeepers on a first-come-first-serve basis from May – October. Fieldwork in 2021 included 287 inspections with inspectors opening 2,266 hives. This included migratory inspections conducted for beekeepers in the fall so the bees could be transported to other states for crop pollination. In 2021, 24 USDA National Honey Bee Survey (NHBS) samples were collected to ensure that new pests and diseases are not threatening colonies.

In 2016, DATCP published the Wisconsin Pollinator Protection Plan, which is an educational resource that identifies voluntary actions residents can take to protect managed and wild pollinators. This plan is divided into the following sections:

• Improving Pollinator Habitat in Gardens & Lawns
• Beekeeping to Maximize Pollinator Health
• Maximizing Pollinator Health & Pollination Services on Farms
• Improving Pollinator Habitat in Prairies, Roadsides & Open Spaces

The DATCP Apiary Program also has a quarterly newsletter. If you would like to sign up for future installments, you can sign up here. Enter your email address, click submit, and select the topic named “Honeybee (Apiary) Information” from the list.

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2021 Plant Industry Bureau Annual Report

The DATCP Nursery Program is housed in the Bureau of Plant Industry. This bureau protects Wisconsin's agricultural and horticultural interests by overseeing and ensuring compliance with laws and regulations involving plant pests, honey bees, nursery plants, Christmas trees, firewood, and seed. Th​e bureau carries out control or eradication programs designed to prevent the spread of harmful pests. These programs include inspection, certification, quarantine, and survey activities.  The bureau also facilitates interstate and international commerce of agricultural products and commodities by certifying plant health and the pest-free status of Wisconsin exports. It maintains coope​rative agreements with the USDA Animal and Pla​nt Health Inspection Service (USDA APHIS), USDA Forest Service, and other state and federal agencies. The bureau annual report, published each April, outlines the regulatory and survey activities conducted over the past year to protect Wisconsin's agriculture, forests, and green industry from insects and diseases that pose an economic and environmental threat.

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^{Aerial application of Btk to reduce spongy moth populations | DATCP image}

Spongy Moth Treatments to Begin Soon

Starting late next week or early the following, DATCP will begin treatments in south western Wisconsin counties for the damaging forest pest spongy moth, formerly known as gypsy moth. The aerial treatments DATCP will be conducting are the most efficient and effective method to delay the impacts associated with spongy moth outbreaks, including the cost of removing dead trees, potential loss of property value and irritation to the eyes, skin and respiratory system in some humans caused by the shed skins of the caterpillars. Residents can expect to see and hear loud, low-flying planes as early as sunrise in the following 17 counties: Barron, Bayfield, Buffalo, Burnett, Chippewa, Crawford, Dunn, Eau Claire, Grant, La Crosse, Lafayette, Pepin, Rusk, Sawyer, Trempealeau, Vernon, and Washburn.

Spraying occurs shortly after caterpillars hatch and depends on favorable weather. The planes spray Bacillus thuringiensis var. kurstaki (Btk), which is a naturally-occurring soil bacteria that kills spongy moth caterpillars feeding on canopy foliage. Btk is not toxic to people, bees, pets, or other animals and is also used in certified organic food production. Treatments will begin in southern Wisconsin and end in northern Wisconsin in mid-July. Maps of treatment areas are available at https://smaerialspray.wi.gov. 

To receive up-to-date information on treatment plans:

• Sign up for email updates.
• Call the hotline toll-free at (800) 642-MOTH.
• Email questions to spongymoth@wisconsin.gov. 

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^{'Blue Dune' Lyme grass is a restricted NR40 plant that cannot be sold | DATCP K. Jerabek}

NR40 Invasive Plants

NR40 is another name for the WI-DNR “Invasive Species Rule” prohibiting the possession, movement, purchase or sale of invasive plants in the state of Wisconsin. The rule is divided into two subcategories based on their presence in the state. Prohibited invasive plants are species that have not become established in state but have potential for high negative impacts. All findings of prohibited invasive species, whether being offered for sale or growing in the environment, will be followed with control efforts. Restricted invasive plants are already found in state and have known negative impacts. Restricted plants cannot be sold, and if they are already growing in the environment, control is encouraged but not required.

Two examples of NR40 plants found at Wisconsin nurseries in 2021 were European frog-bit (Hydrocharis morsus-ranae) and Wild parsnip (Pastinaca sativa). European frog-bit is a prohibited plant that grows in compact, floating masses impacting aquatic life and outdoor recreation. Wild parsnip is a restricted plant which can cause long term rashes or blisters when the sap comes in contact with skin. Due to the various repercussions caused by invasive species, efforts to slow the spread and prevent introduction are encouraged at every level.

By adhering to the NR40 rule, you are assisting in keeping your community and business safe and thriving. Being familiar with the NR40 list provides another level of service when working with the public. If you are unsure of a species, there is a reference list of known synonyms and a sub-list of invasive aquatic plants. There are exemptions for some ornamental cultivars. If you need a special exemption, you can apply for a permit to grow, move, or sell a listed invasive species; i.e. any viable part of the plant (including seeds) for a limited amount of time.

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^{DATCP Field Notes Banner}

Check out Field Notes for Weekly Pest Survey Updates

For the 2022 growing season, DATCP's Pest Survey Program is offering a new weekly email publication called Field Notes. Inside Field Notes, readers will find the same pest monitoring data and maps once provided in the Wisconsin Pest Bulletin, along with current articles on economically important plant pests affecting Wisconsin's field crops, fruits, vegetables, nurseries, and forests. Field Notes replaces the Pest Bulletin as the source for results of our field surveys, inspections, and lab diagnostic work and is a great companion to the monthly What’s Growing On newsletter. Subscribe online.

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Learn More

For more information about Wisconsin's Nursery and Christmas Tree Programs, visit DATCP's Nursery and Christmas Tree Program webpage.

Read past issues of What's Growing On?