NDSU Extension Service - Burke County

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Leafy Spurge & Black Leaf

County Agent News
Dan Folske
June 12, 2017 

Leafy Spurge Control

            Leafy Spurge is an introduced plant which is extremely invasive. It’s yellow flowers can be seen in many areas of the countyLeafy Spurge right now. If left uncontrolled it just continues to spread and replaces native and other desirable plants. That means less productivity on grazing and haying land and also less usable habitat for many wildlife species.

            Leafy Spurge is listed as a Noxious Weed by the state of North Dakota and landowners are required to control it. Control be by chemical (herbicide), mechanical (mowing), or biological (grazing or insects). No one method is perfect and there is no method or combination of methods which will eradicate an infestation. I have seen landowners/producers who have eradicated some very small spots by combinations herbicides and other methods and have seen other infestations reduced in size or density through diligence in application of various control methods.

            A common problem I have seen is making one or two releases of flea beetles and assuming they will control the infestation. I have seen some very good successes with flea beetles and have seen many failures. Soil conditions, vegetative conditions, temperature and other factors play a huge role in biological control. Even the most successful bio control needs to be monitored and often supplemented by other methods. Monitoring of beetle populations is very important.

            Adult beetle activity was observed at some locations in the state last week. That means it is time to monitor your populations. Areas with few or no beetle present need to be considered for additional releases or the use of alternate control methods like mowing or herbicides. Areas with high beetle populations should be considered for collecting and moving. If you have a site with high beetle numbers I would like to discuss possible collections in cooperation with the weed board and neighboring landowners. You cannot hurt a site by over collecting! Sites with an excess beetle population results in the beetles competing for forage (leafy spurge) and the “move off” or “die off” of the adult beetle populations. Even the most thorough collecting leaves more than adequate numbers for maintaining the population on the site.

            Sites should be checked when temperatures are at least 70F and warmer is better. During periods of cooler temperatures the adult beetles will be down in the plant canopy rather than high on the plants. If they are not high on the plants they are difficult to see or to catch with a sweep net.

            If you would like me to check a site with you I would be happy to bring sweep nets and see what we can find. Email me at dan.folske@ndsu.edu or call me at 701-377-2927 (office) or 701-339-1133 (cell).

 

Black Leaves

            I’ve had several calls the past two weeks regarding black or partially black leaves on some trees, especially lilac and green ash. I believe most of these black leaves are frost damage and will not seriously hurt the trees or continue to spread. I’ve also had calls about apples, and strawberries not setting fruit during the same period. In each of these cases blossoms were present during the time we were getting some light frosts and it is probable that the blossoms received just enough frost damage to prevent or about fruit set. My own apple trees are setting fruit normally but I know the frost was extremely variable.

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