{"id":13296,"date":"2026-05-29T10:53:50","date_gmt":"2026-05-29T14:53:50","guid":{"rendered":"https:\/\/extension.umaine.edu\/highmoor\/?p=13296"},"modified":"2026-05-29T11:10:56","modified_gmt":"2026-05-29T15:10:56","slug":"garlic-ipm-newsletter-no-5-may-28-2026","status":"publish","type":"post","link":"https:\/\/extension.umaine.edu\/highmoor\/2026\/05\/29\/garlic-ipm-newsletter-no-5-may-28-2026\/","title":{"rendered":"Garlic IPM Newsletter No. 5 — May 28, 2026"},"content":{"rendered":"
\"Garlic
Garlic field in southern Maine. Photo by Peyton GInakes, Umaine Cooperative Extension.<\/figcaption><\/figure>\n

Good growing conditions have continued, with moderate rainfall and warming temperatures encouraging the start of garlic bulb development. No major new diseases, or progressions in foliar diseases, have been observed at any scouting locations, and plants are generally healthy.<\/p>\n

Insect Pests<\/h3>\n

With several recent warm spells, growing degree days (GDDs) that drive insect development are rapidly accruing. All of the state except Katahdin and the westernmost part of the county have warmed enough for allium leafminer (ALM) adults to emerge, where they have overwintered<\/strong>. As a reminder, ALM has not been found in Maine, but since it has been found in Canada and other New England states, it is good to keep an eye out for its damage. The GDD emergence threshold for onion maggot has also been met in most of the state. In addition to these two fly pests, the southernmost parts of Maine have now warmed enough for onion thrips to emerge. The chart below shows GDD accumulation for each of these three pests in locations represented by the Maine Climate Office GDD maps<\/a>.<\/p>\n

\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
\n

Allium Insect Pest GDDs through May 27, 2026<\/strong><\/h4>\n<\/caption>\n

Location<\/th>\nALM
\n630 GDD33.8F<\/sub><\/th>\n		Onion Maggot
\n390 GDD40F<\/sub><\/th>\n		Onion Thrips
\n140 GDD52.7F<\/sub><\/th>\n<\/tr>\n
Augusta<\/th>\n969*<\/td>\n557*<\/td>\n128<\/td>\n<\/tr>\n
Bangor<\/th>\n941*<\/td>\n557*<\/td>\n109<\/td>\n<\/tr>\n
Calais<\/th>\n880*<\/td>\n507*<\/td>\n83<\/td>\n<\/tr>\n
Caribou<\/th>\n665*<\/td>\n375<\/td>\n54<\/td>\n<\/tr>\n
Cherryfield<\/th>\n910*<\/td>\n506*<\/td>\n89<\/td>\n<\/tr>\n
Clayton Lake<\/th>\n615<\/td>\n333<\/td>\n55<\/td>\n<\/tr>\n
Cutler<\/th>\n687*<\/td>\n289<\/td>\n16<\/td>\n<\/tr>\n
Damariscotta<\/th>\n1031*<\/td>\n603*<\/td>\n129<\/td>\n<\/tr>\n
Dover-Foxcroft<\/th>\n866*<\/td>\n516*<\/td>\n103<\/td>\n<\/tr>\n
Ellsworth<\/th>\n935*<\/td>\n529*<\/td>\n98<\/td>\n<\/tr>\n
Embden<\/th>\n904*<\/td>\n536*<\/td>\n115<\/td>\n<\/tr>\n
Farmington<\/th>\n902*<\/td>\n540*<\/td>\n128<\/td>\n<\/tr>\n
Fort Kent<\/th>\n637*<\/td>\n351<\/td>\n45<\/td>\n<\/tr>\n
Fryeburg<\/th>\n992*<\/td>\n607*<\/td>\n155*<\/td>\n<\/tr>\n
Greenville<\/th>\n633*<\/td>\n349<\/td>\n66<\/td>\n<\/tr>\n
Katahdin<\/th>\n280<\/td>\n119<\/td>\n10<\/td>\n<\/tr>\n
Kittery<\/th>\n1158*<\/td>\n708*<\/td>\n172*<\/td>\n<\/tr>\n
Lewiston<\/th>\n957*<\/td>\n571*<\/td>\n135<\/td>\n<\/tr>\n
Lincoln<\/th>\n850*<\/td>\n499*<\/td>\n94<\/td>\n<\/tr>\n
Houlton<\/th>\n757*<\/td>\n442*<\/td>\n74<\/td>\n<\/tr>\n
Jackman<\/th>\n691*<\/td>\n382<\/td>\n68<\/td>\n<\/tr>\n
Millinocket<\/th>\n799*<\/td>\n476*<\/td>\n91<\/td>\n<\/tr>\n
Newry<\/th>\n915*<\/td>\n548*<\/td>\n136<\/td>\n<\/tr>\n
Northfield<\/th>\n879*<\/td>\n496*<\/td>\n84<\/td>\n<\/tr>\n
Portland<\/th>\n1013*<\/td>\n588*<\/td>\n124<\/td>\n<\/tr>\n
Sanford<\/th>\n1098*<\/td>\n676*<\/td>\n196*<\/td>\n<\/tr>\n
Rangeley<\/th>\n661*<\/td>\n368<\/td>\n70<\/td>\n<\/tr>\n
Thorndike<\/th>\n894*<\/td>\n521*<\/td>\n108<\/td>\n<\/tr>\n
Topsfield<\/th>\n779*<\/td>\n451*<\/td>\n77<\/td>\n<\/tr>\n
W Rockport<\/th>\n946*<\/td>\n539*<\/td>\n109<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

The table lists GDDs from Maine Climate Office website<\/a> and numbers marked with an asterisk (*) indicate that sufficient GDDs have been met in that location for pests to emerge, and regular scouting as outlined below is warranted.<\/p>\n

Scouting for Insect Pests<\/h3>\n
\"Onion
Onion thrips (arrow) on garlic midvein with light scarring. Photo by Peyton Ginakes, UMaine Extension.<\/figcaption><\/figure>\n

Just because enough GDDs have accrued in an area for pests to develop does not<\/strong> mean that they are present. These numbers are simply a timely reminder to scout for them, and install protective measures as necessary based on your knowledge of prior damage or infestations. Here is a quick overview of how to scout for each pest:<\/p>\n