Plant Clinic

Pest Management Calendar

This calendar provides information about life cycle events for common Missoula County plants, pests, and diseases.

April 2026

This Month

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29	30	Mar 31	Apr 1	2	3	4
						12:00 am Engraver beetle adults start to lay eggs in Pine trees

5	6	7	8	9	10	11
12:00 am Engraver beetle adults start to lay eggs in Pine trees	12:00 am Treat broadleaf annual weeds				12:00 am Treat for Podgall Midge, Rust & Blister Mites, and Petiole-gall aphids.

12	13	14	15	16	17	18
12:00 am Treat for Podgall Midge, Rust & Blister Mites, and Petiole-gall aphids.	12:00 am Check for Tent Caterpillars			12:00 am Ash leaf-curl aphids emerge - TREAT NOW		12:00 am Check for Boxelder Leafroller

19	20	21	22	23	24	25
12:00 am Check for Boxelder Leafroller	12:00 am Check fruit trees, shrubs, and green ash for aphids		12:00 am Elm Leaf beetles emerge - NO NEED TO TREAT!		12:00 am Check for Petiole-gall Aphids - TREAT NOW!

26	27	28	29	Apr 30	May 1	2
12:00 am Check for Petiole-gall Aphids - TREAT NOW!	12:00 am Treat for White Pine Weevils		12:00 am Check for hatching Pine-needle Scale Crawlers
	12:00 am Put up Codling Moth traps in apple trees		12:00 am Time to fertilize lawns

Engraver beetle adults start to lay eggs in Pine trees (Day 1 of 2 )

Starts 12:00 am

Engraver beetle adults start to lay eggs in Pine trees (Day 2 of 2 )

Until 11:00 pm

Treat broadleaf annual weeds (Day 1 of 4 )

Starts 12:00 am

Treat broadleaf annual weeds (Day 2 of 4 )

All Day

Treat broadleaf annual weeds (Day 3 of 4 )

All Day

Treat broadleaf annual weeds (Day 4 of 4 )

Until 11:00 pm

Treat for Podgall Midge, Rust & Blister Mites, and Petiole-gall aphids. (Day 1 of 3 )

Starts 12:00 am

Treat for Podgall Midge, Rust & Blister Mites, and Petiole-gall aphids. (Day 2 of 3 )

All Day

Treat for Podgall Midge, Rust & Blister Mites, and Petiole-gall aphids. (Day 3 of 3 )

Until 11:00 pm

Check for Tent Caterpillars (Day 1 of 3 )

Starts 12:00 am

Check for Tent Caterpillars (Day 2 of 3 )

All Day

Check for Tent Caterpillars (Day 3 of 3 )

Until 11:00 pm

Ash leaf-curl aphids emerge - TREAT NOW (Day 1 of 2 )

Starts 12:00 am

Ash leaf-curl aphids emerge - TREAT NOW (Day 2 of 2 )

Until 11:00 pm

Check for Boxelder Leafroller (Day 1 of 2 )

Starts 12:00 am

Check for Boxelder Leafroller (Day 2 of 2 )

Until 11:00 pm

Check fruit trees, shrubs, and green ash for aphids (Day 1 of 2 )

Starts 12:00 am

Check fruit trees, shrubs, and green ash for aphids (Day 2 of 2 )

Until 11:00 pm

Elm Leaf beetles emerge - NO NEED TO TREAT! (Day 1 of 2 )

Starts 12:00 am

Elm Leaf beetles emerge - NO NEED TO TREAT! (Day 2 of 2 )

Until 11:00 pm

Check for Petiole-gall Aphids - TREAT NOW! (Day 1 of 3 )

Starts 12:00 am

Check for Petiole-gall Aphids - TREAT NOW! (Day 2 of 3 )

All Day

Check for Petiole-gall Aphids - TREAT NOW! (Day 3 of 3 )

Until 11:00 pm

Using Integrated Pest Management (IPM) strategies

IPM means getting to know your pests.

When is the pest MOST vulnerable, infective, or invasive?
When is the pest most vulnerable to least-toxic management strategies?
What is the least-toxic management tool that can be used successfully?

IPM optimizes plant health through the following:

Managing garden and landscape soils to promote drainage and aeration
Maximizing soil health by adding organic matter and properly timed fertilizers.
Pruning and irrigating based on the needs of particular plants.
Knowing the plant's level of susceptibility to pest damage.