Green & Growing

Poisonous plants bring to mind those Most serious are plants which are fatal used in fiction murder mysteries — such if eaten, belladonna or Deadly as the castor bean or ricin written by Nightshade, delphinium or Larkspur, Agatha Christie and aconite, or monkshood Foxglove, morning glory seeds, azaleas, written by Ellis Peters. These same plants and periwinkle — as well as the previmay be growing in our gardens because of ously mentioned poisons. The seeds of their pleasing flowers or foliage. However, stone fruits and apples are poisonous if gardeners should be aware of their charac- eaten in large amounts. teristics and treat them with caution. There are other common plants that may also be harmful, causing fatalities when eaten or skin irritation when touched. The next category lists plants which cause vomiting or diarrhea if eaten — including yarrow, allium, columbine, marsh marigold, poinsettia, holly berries and others. An online search revealed a longer-than-expected list of these plants. The University of California has a list of poisonous plants with details as to the potential harm that may occur. That list places plants in four categories. A third category lists plants which contain oxalate crystals in the juice or sap which can cause throat swelling, breathing difficulties or stomach upset. Plants in this category include begonia, caladium, dieffenbachia, rhubarb leaves, calla lilies and others.

GREEN AND GROWING By Linda G. Tenneson

Managing the Japanese beetle

ST. CLOUD Minn. — As the growing season continues with ornamental and producing plants, we need to look towards managing pests. One pest that can cause major damage to your plants is the Japanese Beetle. They start to appear in late June to early July and can last into September. You can identify adult Japanese Beetles by their metallic green head and thorax, and their brown copper wing covers. Their larva, also known as white grubs, can be identified by their tan head and white C-shaped body. Their legs will also be visible to the naked eye.

Adult Japanese beetles will feed on leaves, flowers, and fruits of more than 300 different types of plants, making them a common pest for all growers. They often damage plants by eating the soft tissue on leaves between major veins skeletonizing the leaves and leaving a lace-like appearance. The blossoms of flowering plants are often damaged too.

The damage caused by Japanese beetles is mostly cosmetic and won’t cause any long-term injuries to the plant. However, young or unhealthy plants may become stunted, injured, or even killed from severe, persistent feeding. The larvae feed on grass roots,

decreasing the grass’s ability to take up water. This can leave dead patches of grass on your lawn. Dead patches caused by larva can be identified if the patches can be rolled like a carpet due to lack of roots. Physically removing the beetles can be the most effective practice for small gardens and yards. Knocking beetles off the plants into a bucket of soapy water will kill the beetles. It is best to do this in the morning or the evening when beetles are slow. You can also use a physical barrier, like an insect net, to prevent damage. However, do not cover plants in bloom because it will prevent pollination of fruiting plants. Do not use Japanese beetle traps to manage beetles. These traps use a pheromone to attract beetles and can bring more beetles and other insects into your garden or yard. Pesticides can be used to manage population, but it is not recommended. If you do use pesticides, make sure you are following the label and proper practices to avoid damages and injuries. This article was submitted by Kaitlyn Czeck, University of Minnesota Extension. v Restrictions in place for Chlorpyrifos

Chlorpyrifos is a broad-spectrum organophosphate insecticide (IRAC group 1B) used on nursery plants, ornamentals, wood structures, cattle, roach bait stations, and other habitats. Chlorpyrifos has been detected in surface waters in Minnesota through the Minnesota Department of Agriculture’s Ambient Water Monitoring Program and is currently designated as a “Surface Water Pesticide of Concern.”

The Environmental Protection Agency has revoked all food and feed tolerances for chlorpyrifos and the MDA did not renew the registration of chlorpyrifos products with food and feed uses in 2022. This means that chlorpyrifos products with food and feed uses cannot be sold or distributed in Minnesota, nor applied to food and feed crops.

Non-agricultural uses of chlorpyrifos such as on golf course turf, industrial sites, greenhouse and nursery production, sod farms, and wood products are still allowed.

For disposal of unused product contact the product registrant about return options. If they will not take the unused product, local disposal can be made through the MDA Waste Pesticide Program. Visit https://www.mda.state.mn.us/ for more details.

This article was submitted by the Minnesota Department of Agriculture. v

The fourth category contains plants where the juice, sap or thorns will cause skin rash or irritation such as poison ivy, Balsam Fir, bougainvillea thorns, English Daisy, bleeding heart, rubber tree and fig. Our state flower, the Lady’s Slipper, can cause skin irritation when touched.

Several plants fit into more than one category such as Lily of the Valley, hydrangea, cardinal flower and oleander which are fatal if eaten and can cause a rash when handled. From my own experience, not all potentially skin irritating plants will irritate all people.

However, gardening is best done while wearing gloves as much as possible to prevent skin irritation as well as to protect fingernails. Skin exposure may be minimized by a thorough hand washing as well as washing gloves and gardening clothing. The oil in poison ivy, urushiol, can be a particular problem because it can remain on clothing, shoes and tools for extended periods of time. While many of these plants can be cultivated with care, some like oleander and Angel’s trumpet, Brugmansia are so potentially toxic they should not be grown when pets or children may encounter them.

Bulbs such a hyacinth, narcissus and daffodil are not ones people would think of eating, but their toxicity is the reason that squirrels will dig them up and then leave them after realizing they are dangerous.

The Texas A & M Agri Life Extension also has a list of poisonous plants and the symptoms they cause to children or adults. Several other state extension websites contain useful information. And the U.S. Department of Agriculture Natural Resources Conservation Service and University of Minnesota Extension websites list the damage that some plants can cause to livestock.

Consult medical care whenever poisoning is suspected.

Linda G. Tenneson is a University of Minnesota master gardener and tree care advisor. v