White Mulberry
This week we’ve been getting questions on how to manage white mulberries in the garden. White mulberries (Morus alba) is an introduced small tree/large shrub from China. It was originally brought over as a potential food source but it quickly escaped cultivation. The fruit is tasty and is enjoyed by many animals such as raccoons, opossums, and birds. These critters will then deposit the seed in our gardens. Often we find it growing in the fence line or in poking out of the shrubs. Small volunteers can be managed by pulling them out or digging them out of the ground. Larger, more established volunteers will need to be cut down to ground level. Larger plants will sprout and will need to be cut again to prevent the plant from re-establishing itself. Alternatively they could be cut down about one inch off the ground and apply an herbicide with the active ingredient, triclopyr to the fresh cut. White mulberry are invasive and generally considered a non-desirable plant for the landscape.
White mulberry can have up to five or six different leaf types on the same plant. This can made identification challenging if you are not familiar with them. Also, we do have a native red mulberry that can sometimes be misidentified. Check out this publication on how to correctly tell the two plants apart from our friends at Purdue.
Slime Mold
Slime mold is not a mold and not really slime. They happen to be a bunch of undifferentiated cells that can crawl along the surface of the ground including mulch beds, vegetable gardens, and flower beds. They are a sight to see however, they can appear alarming. Slime mold is not harmful or toxic but we do not recommend trying to eat any of it. As we start to dry out in the Omaha metro we will start to see slim mold form thick crusts that help protect spores until the weather becomes favorable. They do not need to be managed. However, if you are not a fan of them just wash them off with a strong stream of water or even brush them off with a stiff broom.
Bagworms
Bagworms have recently emerged and started to munch away on our favorite evergreen plants. Bagworms are like caddisfly, they make a protective cases out of plant parts. Bagworms are known to feed on a range of trees and shrubs but are most damaging on evergreens. They are easier to manage when small. Hand picking is an option along with lower impact pesticides such as Bacillus thuringiensis or spinosad. As they get larger more conventional pesticides will be needed and they need to be applied before the bags closes late summer. Once closed all that can be done is to remove by hand. Urban Entomologist Dr. Jody Green has a great info sheet about this insect and you can locate it here.
Powdery Mildew
Powdery mildew is starting to show up on peonies. Powdery mildew shows up as a white, sometimes grey’ish film on the adaxial (top) side of the leaf. In some extreme infections it can also be found on the stems. It is an obligate parasite which means it can only live on live plant tissue and if the plant dies it will too. Culture management options would include improving air circulations and and good fall sanitation. Most fungicides on the market will also help. University of Minnesota Extension has some great information if you would like to learn more.
Aster Yellows
Here at the office we are starting to see some of our coneflower looking odd. These are probably signs of aster yellows. This disease is caused by bacteria-like phytoplasma. Aster yellows can be found on all asters from goldenrod, dandelion, coneflower to lettuce. Some common signs include purple veins, deformed flowers, green flowers, bushy growth, and flower proliferation. It can be mistaken for herbicide drift. Aster yellows is transmitted by the aster leafhopper and once infected there is no treatment for the plant. The best option is to remove the plant from the garden and clean any tools that were used. University of Minnesota Extension has great publication that you can check out if you want to learn more.
