These pesky weeds keep coming up all over my yard, and it’s really hard to keep up with them. I have tried pulling them up and sometimes spraying them with Roundup, but they keep coming back. They almost seem to enjoy the Roundup! What the heck are they, and how can I get rid of them once and for all?
Thank you for also providing a photo with your question. According to UC master gardener Carol Hunter, the weed photograph you enclosed shows the seedling stage of the Epilobium ciliatum (in the evening primrose family). Its seeds are dispersed by the wind, it germinates rapidly, it grows vigorously, and few herbicides provide effective control.
There are several common plant names used for this weed, but most frequently, it is referred to as the “Northern willowherb.” It’s particularly troublesome for professional nurseries in Oregon and California.
The most effective means to control this weed are hand-weeding and application of a postemergent herbicide. It is recommended that you carefully read the instructions on any herbicide product before purchase to ensure that it has application to this weed and that the timing and method of application are correct.
To be effective in control of willowherb, you need to remove it before seeds develop. Oregon State University has an excellent article about this weed on its website with photographs of various stages of the plant. Find it at http://oregonstate.edu/dept/nursery. Other resources include “Weeds of California and other Western States” (the University of California’s two-volume encyclopedia on this topic) and at the university’s Integrated Pest Management website, www.ipm.ucdavis.edu/PMG/WEEDS/willowherbs.html.
Most likely, this was a side effect of weird winter weather. Dry December weather and lack of sufficient chill hours caused poor fruit set in some berry varieties, particularly marionberries. According to local blackberry farmers, poorly timed spring rains in March also knocked back the fruit set. Instead of consistent clumps of berries, vines had “scattered bloom” or aborted their fruit altogether.
Another possibility is pest damage. Both stink bugs and spotted wing drosophila attack blackberries. For a definitive answer, bring a sample of your spotted berries in a sealed plastic bag to the cooperative extension office during the master gardener hours listed on this page.