No. 4/May 23, 2017
Fire Blight vs. Bacterial Blast
We're beginning to see symptoms of fire blight in central Illinois. The University of Kentucky Extension service has been reporting high risk of fire blight this spring, so we were expecting to see symptoms show up sooner rather than later. The Plant Clinic received the first two samples of suspect fire blight earlier this week, one pear, the other crabapple.
White Pine Decline
Several eastern white pine samples have made their way to the U of I Plant Clinic this spring. The samples all arrived with similar descriptions of overall symptoms, "Dying trees with thinning, yellowing and browning needles." These samples are always somewhat frustrating because they usually lack any pathogens to explain the symptoms. Incubated needles and branches rarely produce any diagnostic clues. The lack of pathogen(s) leads us to attribute the symptoms to white pine decline, a condition caused by an environmental or abiotic stress.
Rabbit Damage
Rabbits are gnawers, loving to eat branches and bark (during the winter) and tender plants during the spring and summer. They'll munch grass down to the crowns, eat developing peony shoots, vegetable transplants, and some bulbous plants like lilies and tulips. They'll occasionally munch on hostas, but most severe hosta damage is usually from deer, which will devour the blade and leave the leaf petiole. Angular cuts or chewing is an indicator of rabbit damage. When feeding on woody twigs close to the ground, their angled cuts looks similar to those made by pruners.
Squirrel Damage
Squirrels are diggers, and will eat bulbs (mainly tulips and crocus, but not so much daffodils) or dig up plants in order to use the loosen soil to store their cache of nuts and other food. They aren't commonly known to feed on flowers and vegetables unless other food sources are limited.
May Beetles
Adult May beetles are present throughout the state. These are 1-inch long, stocky beetles that are active at night. Many species occur in Illinois, all in the scarab genus, Phyllophaga. As such, they vary in color and somewhat in size, being some shade of brown, from tan through dark chocolate brown. The ones that are out now are reddish brown.
Neonicotinoids and Milkweeds
A milkweed plant purchased on April 27, 2017 at a home improvement box store in the New Orleans, Louisiana area contained a tag in the pot stating that it had been treated with a neonicotinoid insecticide. The person who bought the plant returned to the store and found approximately 100 more milkweeds with the same tag inserted in their pots. Her finding was reported to National Garden Clubs who contacted Home Depot on May 1. On May 2, a Home Depot official reported back that the plants were labeled in error, that they were not treated with neonicotinoids.
Modified Growing Degree Days (Base 50°F, March 1 through May 18)
Insect development is temperature dependent. We can use degree days to help predict insect emergence and activity. Home, Yard, and Garden readers can use the links below with the degree day accumulations above to determine what insect pests could be active in their area.