Blister beetles and a vegetable problem reminder

Blister beetles are a long, narrow beetle which feeds on many different garden and agricultural crops.

Blister beetles are showing up in yards and gardens as well as agricultural crops. Blister beetles are a long, narrow beetle which feeds on many different garden and agricultural crops. The most common blister beetles in our area are solid black or gray colored. A less seen variety is an iridescent green and reddish beetle which is larger than the other two. They commonly feed on caragana bushes, clematis, green beans, Baptisia and other flowers, vegetables and garden plants. They also feed on alfalfa, canola and other ag crops. All three varieties will feed together on the same plants. They have a strong tendency to feed together in groups rather than individually in scattered areas. Once a group begins feeding on a plant they can consume most if not all of the plant in a relatively short time.

They are called blister beetles because when threatened they secrete a substance that is toxic and is used to protect against predators. It is quite caustic and can cause blistering on peoples’ skin if encountered. In the adult form they are a problem for this reason as well as their plant feeding habits. The substance they secrete is very toxic to livestock, especially horses, if consumed. Caution for livestock owners is suggested in especially alfalfa hay that was cut with a hay conditioner. The crushed, dead beetles are still toxic to livestock so care should be taken.

Interestingly, blister beetles are also beneficial at a particular stage of their life. Their eggs are laid in the ground, and one of the most preferred foods of the larval blister beetles in North Dakota is grasshopper eggs which are also laid in the ground. Grasshopper numbers are up after two years of dry weather, and the blister beetle population has followed this increase with the increased larval food source.

Insecticides that are registered for gardens will control them. For those wishing to use an organic approved insecticide, those containing Spinosad are very effective. With all insecticides, read the label to be sure the product can be used on the plants to be treated. And follow mixing and application information as well.

Blossom-end rot prevention

Blossom-end rot is caused by a plant not having enough water.

Tomatoes, peppers, as well as summer and winter squash all can show the problem of blossom-end rot. This condition is not a disease caused by a bacteria or fungus. It is caused by the plant not having enough water. When the plant does not have enough water, it begins to abort it fruits to survive.

By providing enough water, the plant can resume producing good fruit. Deep watering that soaks the soil deep under the plant is the key to helping the plant. Light daily surface watering does not provide enough water and actually promotes blossom end rot.

Other things that can be done to prevent blossom end rot are keeping rototilling and hoeing of weeds back at least 3 feet from the plant in all directions. Mulching around the plant with straw, newspaper, cardboard or grass clipping from a lawn that has NOT been sprayed this summer for weeds will conserve moisture and reduce weed competition. Together with deep watering, mulching should make the problem disappear for the rest of the season.


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