Is Kerb herbicide safe on established, mulched blueberries ?
Is it safe to use kerb herbicide on established blueberreis mulched with sawdust. ? There are blueberry roots in the mulch. Will such a treatment not affect the bushes ?
Outside United States
Generally, Kerb is considered a relatively safe herbicide for use on perennials. Its mode of action is reducing cell division so it is very effective against germinating seeds and small plants. Since the herbicide's active ingredient is only in the upper soil layer, larger plants can easily withstand it effects. An organic mulch such as sawdust will bind up a lot of the herbicide and I generally recommend that growers use the higher rate of the recommended range when applying over a mulch and the lowest rate in sandy soils. It is possible that the herbicide could have some effect on root growth if all the roots are in the mulch and none are in the soil below. If the plants are mature and growing well, it is unlikely you would notice the effect but if the plants are small with all their roots in the mulch you might see it affect their growth. If you think that is likely I would recommend treating only a few plants to see the effect. A lot of things can cause poor growth so if some plants are growing poorly and other look fine I would suspect a different cause than the herbicide.