April 2012

New blight on boxwood also threatens Japanese spurge

Early symptom of boxwood blight. Photo courtesy Connecticut Department of Agriculture

A worrisome new fungus found on boxwoods also threatens Japanese spurge, the popular ground cover, according to Purdue University’s Plant Pest Diagnostic Laboratory.

Boxwood (Buxus) blight (Cylindrocladium pseudonaviculatum) has been confirmed in Ohio, North Carolina, Connecticut, Virginia, Maryland, Pennsylvania, New York, Rhode Island, Massachusetts and Oregon. The same fungus recently was found to cause the disease on Japanese spurge (Pachysandra terminalis). The disease was first reported late last year in Connecticut, where the disease was found on boxwoods in a residential landscape. In the other states and Canada, the blight has been found on boxwoods at nurseries and growers.

Although boxwood blight has not been found in Indiana, the Purdue plant experts recommend that property owners and landscapers be vigilant if planting new boxwoods or Japanese spurge in landscapes this spring. The Purdue lab asks to be contacted if you see symptoms on boxwoods or Japanese spurge.

“Recently, plant pathologists at the Connecticut Agricultural Experiment Station found that the fungus, which causes boxwood blight, can also cause disease on Pachysandra ground cover,” the Purdue lab reported March 19, 2012. Japanese spurge (Pachysandra terminalis) is part of the boxwood family.

The Connecticut research exposed healthy pachysandra plants to the spores of the fungus and within 10 days, lesions or small round spots developed. Three weeks after exposure, “many of the leaves with lesions yellowed and dropped,” the Purdue lab said. “This raises significant concerns about pachysandra as a potential source of (the spores) for infection of boxwood and vice versa.”

The leaf spot and dieback symptoms on the spurge may be confused with a common and widespread disease of Pachysandra, known as Volutella blight (see photo below).

Volutella blight on Japanese spurge (Pachysandra terminalis). Photo courtesy Purdue University Plant Pest Diagnostic Laboratory

You Can Grow That! April 2012: Tender, Summer Bulbs

Pineapple lily and oxalis add texture in the hosta garden.

For many gardeners, summer bulbs are as mysterious as the exotic places they come from.

Most bulbs that bloom in summer look different than their spring-blooming relatives. Many spring bulbs, such as tulips and daffodils, have flat bottoms and pointy tops. Summer bulbs are more likely to look like a sprawling creature from the deep.

The term summer bulb includes corms (gladiolus), rhizomes (daylily) and tubers (begonia). Gardeners seem to be most familiar with cannas, caladiums, elephant ears (Alocasia or Colocasia), gladiolus and dahlias, which already are staples in perennial beds. But interest is on the rise for the less familiar summer bulbs, such as pineapple lily (Eucomis) and rain lilies (Zephyranthes).

Summer bulbs, from their ornamental foliage to fragrant flowers, have shot up in popularity because people are spending more time in their gardens and there’s more interest in cutting flowers to bring them indoors for enjoyment.

Summer bulbs tend to bring a lush, tropical feel to the garden, which some people have a hard time working into their landscape. However, gardening should be experimental. There’s nothing wrong with trying new things and moving plants around to get the look you want. Summer bulbs also are wonderful space fillers with perennials or, when planted in a pot, a focal point in the garden.

Many summer bulbs are tender, such as dahlais, and need to be dug after the first frost and wintered over. Others are perennial, such as lilies (Lilium), which winter over fine in the Indiana garden..

A drawback to planting tender summer bulbs may be confusion about when to dig them up if you plant to store them for the winter. Inexpensive tender bulbs should be treated as annuals and discarded at the end of the season.

Other, more valuable tender bulbs, can be grown in pots that are sunk in the ground and raised after the first frost for storage in a cool place that will keep them from freezing, but not too warm so they don’t sprout. Others plant the tender bulbs right in the ground and dig them up after the frost.

In general, tender bulbs should be dug after the first frost kills back the foliage. Brush off the soil and cut off the foliage that has been killed by the frost. Store the bulbs in dry peat moss, wood shavings or similar product, or just place them in a paper bag that remains open. Circulation is important. Check the bulbs periodically and remove any that are soft or mushy.

You Can Grow That! appears the 4th of the month. It was started by C.L. Fornari at Whole Life Gardening.