Garlic IPM Newsletter No. 10 — June 18, 2025
Irrigation
Garlic, like many crop plants, needs about an inch of water per week. Even though the forecast has called for a good number of rainy days in the last few weeks, showers have been very scattered and some areas haven’t actually accumulated much rainfall. Portland, for instance, has only gotten about 1″ since June 1. Use a rain gauge or a nearby weather station for the most accurate information. Hot temperatures throughout the state are forecasted through the weekend and early next week.
Garlic has entered the “bulb enlargement” stage of growth, and ample water is needed to help bulbs fill out. Where rainfall is not adequate, irrigation will be key for good bulb size. Ensure that plants receive roughly 1″ per week (this equals 0.62 gallons per sq ft), or more during periods of extreme heat. Also remember that wet foliage is conducive to the development of disease, so using drip irrigation where possible will be beneficial. In the home garden, watering can be directed at the base of plants rather than spraying over tops.
Thrips
Onion thrips numbers are increasing slowly at all scouting locations. Damage has continued to accrue but no location has yet reached the 1 thrips/leaf threshold. Continue scouting your plants to determine when control measures are warranted.
| Scouting Location | Thrips (per leaf) as of June 17, 2025 |
|---|---|
| Buxton | 0.09 |
| Monmouth | 0.15 |
| Topsham | 0.04 |
| Washington | 0.15 |
Diseases
Conditions are very favorable for the continued development of fungal pathogens. Scout your fields for symptoms of Botrytis leaf blight, purple blotch/stemphylium, and downy mildew in conjunction with using the NEWA forecasts. Continuing with 7-10 day spray programs is recommended where disease is present.
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.
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