Garlic IPM Newsletter No. 9 — July 2, 2026
Scapes have been harvested throughout southern and central Maine, and garlic crops look good for mid to late July harvest. Bulbs will continue to develop over the next week or two, then begin to senesce. Harvest is typically 3-4 weeks after scaping. It is advisable to stop irrigating two weeks before harvest so as to promote maturation and discourage bulb diseases.
| Location | Thrips (per leaf) as of June 30, 2026 |
|---|---|
| Buxton | 0.09 |
| Monmouth | 0.07 |
| Topsham | 0.84 |
| Washington | 0.09 |
Thrips were above the one per leaf threshold in Topsham last week, but are back below threshold for all scouting locations as of this week. That said, current hot and dry conditions favor their development, and it is likely that populations will grow over the weekend. Those who have begun spraying for thrips should continue on a 7-10 day schedule; remember to rotate IRAC (resistance) groups.
Photo by Peyton Ginakes, UMaine Extension.
Bulb Diseases
Challenging environmental conditions, like this week’s major heat wave, often stresses plants that have diseased root systems but that may have appeared healthy until that point. This occurs because diseased roots cannot take up sufficient water and nutrients during periods of high demand, and symptoms can appear as suddenly yellow, wilting, or dead plants (as shown in the photo to the right). This is distinct from tip dieback and colonization by foliar pathogens.
If you see this happening in your garlic at this point in the season, there is likely an underground culprit. It is best to dig up and examine a full plant or two. Roots may be reduced, absent, or discolored, and bulbs may look discolored, wet, rotten, or swollen. Sometimes discoloration appears only on internal bulb tissue. Additionally, small black sclerotia (hardened fungal structures) may be present. You can submit plants the UMaine Plant Disease Diagnostic Lab to identify the disease and learn what steps should be taken to manage it.
Diseases that may cause late season bulb problems in garlic include Fusarium, Botrytis neck rot, white rot, and rarely, anthracnose. These diseases vary in how commonly they occur and their persistence. Bloat nematode and severe bulb mite infestations may also result in similar symptoms. In all cases, it is recommended to rotate away from alliums for at least four years; some pathogens and pests require a much longer rotation period. Additionally, the crop should not be used as seed for new plantings. Further management recommendations are specific to the pest or pathogen at hand.
Note: There will be no newsletter next week
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.
University of Maine Cooperative Extension is an equal opportunity institution and provider committed to nondiscrimination. For more information, visit extension.umaine.edu/nondiscrimination.