June 23, 2017

Plant and Insect Diagnostic Clinic Update – June 23, 2017

Symptoms and signs of willow leaf spot cause by the fungi Monostichella salicis

Symptoms and signs of willow leaf spot caused by the fungi Monostichella salicis. Top: leaf spot (symptoms), center fungal bodies (signs), bottom spores (signs within the fungal bodies). photos by Lina Rodriguez Salamanca

Growing Annual Geraniums


Annual geraniums are popular indoor and outdoor flowering plants.  The variety of flower colors, leaf shapes, colors, and growth habits make this plant ideally suited for home landscapes.  These versatile plants are excellent as annual bedding plants, in hanging baskets, and in containers.  Annual geraniums are not actually "true" geraniums as they are members of the genus Pelargonium. True geraniums are perennials in the genus Geranium.

Emerald Ash Borer Confirmed in 5 More Iowa Counties

Map showing emerald ash borer distribution in Iowa

The emerald ash borer (EAB) was confirmed in 5 more Iowa counties on June 15, 2017.  New, documented infestations in Benton, Buena Vista, Floyd, Howard, and Warren counties mean that EAB is now confirmed in more than half of Iowa's counties.  See the map below and read more about the most recent discoveries in the Iowa State University Extension and Outreach news release from June 15, 2017.

Dividing Irises


Recommendations for when to divide irises depend on the species. See the Iowa State University Extension and Outreach Yard & Garden news release from June 22, 2017 for information on how to maintain a colorful, attractive iris planting.

Handling Issues with Raspberry Plants


Raspberries are popular with many home gardeners. They’re easy to grow, and perform well in most gardens and provide a tasty and nutritious fruit.  However, gardeners can run into issues with heat, weeds and pruning that can curtail yields.  Read more about raspberry plant problems in the Iowa State University Extension and Outreach Yard & Garden news release from June 14, 2017.

Seed Mix for Monarchs and Bees Developed by Iowa State


Iowa State University Extension and Outreach pamphlet ENT0047, "Monarch Seed Mix High Diversity" is now available on the Extension Store.  Listed are species of milkweeds and other forbs and grasses that have done well in ISU research trials and can be planted for the benefit of monarch butterflies as well as pollinators.  Seeding rates per acre, flower bloom time and preferred soil conditions are listed.  Read more about this publication in the Iowa State University Extension and Outreach news release from