Cooperative Extension at Highmoor Farm

Garlic IPM Newsletter No. 1 — April 17, 2025

Garlic Season Begins

Garlic in southern and midcoast Maine is emerging and it is time to prepare for managing pests in your crop. Here are the basics:

1. Anticipate potential problems by considering the pests or diseases you encountered in previous years. Most garlic diseases persist, and several insect pests overwinter, in soil and crop residues. If you encountered problems in past seasons, identify them and be prepared to manage for them.
2. Scout your crop regularly. Set up a schedule to examine a subset of plants. In large fields, inspect three plants in ten randomly chosen spots across the field (30 plants total) on a weekly or biweekly basis. In smaller plantings or home gardens, one or two spots will do. Look for spotty emergence, foliar lesions, leaf distortion or discoloration, or general stunting. Investigate issues promptly via the Maine Plant Diagnostic Lab or by emailing Peyton Ginakes.
3. Set up your toolkit now. Forecasting tools are available to predict the emergence of several pests and diseases of garlic and other allium crops. These are based on specific phenological models. This newsletter will primarily use the NEWA platform for tracking Growing Degree Days (GDDs) and other environmental factors that enable pest development. Learn more about how to use this resource below!

More about NEWA

NEWA is a platform that uses weather data from hundreds of stations across the United States to create real-time crop production tools specific to users’ regions. Maine is a partner state, so anyone in the state can create a free account. Creating an account allows you to choose and save your location and the pest models relevant to you. You can watch a quick tutorial on how to set up an account and use the website.

You may notice that there are only a few locations in Maine on the NEWA map. Stay tuned because more will be installed over the next several years, thanks to congressional funding awarded to Extension specialists Sean Birkel and Lily Calderwood! For now, use the location closest to you (even if it is in New Hampshire). You can also find GDD models on Sean Birkel’s Maine Climate Office website, shown in the table below. You may notice that there are several “base” models to choose from – for Maine garlic pests, 40°F is most relevant. In NEWA, this is automated based on the pest.

GDD₄₀ accumulation as of Apr. 15, 2025 (Maine Climate Office: https://mco.umaine.edu/growing/gdd_maps).

In NEWA, you will see there are many “tools” – or models – to peruse and/or save to your dashboard. There are two primary tools pertaining to garlic: Onion Maggot and Onion Diseases. You can check these any time to see how conditions favor the development of this particular insect pest and three fungal pathogens. Future newsletters will explain how to use these in more detail, along with other cultural and pest management practices.

Peyton Ginakes, PhD
Research Associate
University of Maine Cooperative Extension
Highmoor Farm
52 US-202
Monmouth, ME 04259
(207) 933-2100

This project is funded by a Specialty Crop Block Grant through the Maine Department of Agriculture, Conservation, and Forestry. Funding for the Maine 2024 Specialty Crop Block Grant Program was made possible by a grant/cooperative agreement from the USDA Agricultural Marketing Service. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the USDA.

Where brand names or company names are used, it is for the reader’s information. No endorsement is implied nor is any discrimination intended against other products with similar ingredients. Always consult product labels for rates, application instructions and safety precautions. Users of these products assume all associated risks.

The University of Maine System is an equal opportunity institution committed to nondiscrimination.