MAY
2010

 

 

 

By
B. Rosie Lerner
 
Purdue
Extension
Consumer Horticulturist

 

 

 

 

 

05-06-10

Question and Answer


Q. The last couple of springs we have had this beautiful flower in our bed, with a nodding, bell-shaped bloom checkered with dark maroon and creamy white. We didn't plant it, and there is only one. Can you tell us what it is, and where we can buy more?

 A. That would be Fritillaria meleagris, commonly known as the checkered lily or guinea-hen flower. This dainty spring-flowering bulb reaches just 8-12 inches tall, thrives in moist soil, and performs well in full sun or light shade. You should be able to purchase the bulbs for fall planting from local garden centers and mail-order bulb suppliers.

Q. We have concord grapes, and every year they look great until they start to ripen. They start to turn to raisins and drop off. Someone told us this was grape rot. What can we do to prevent it?

A. Black rot is the most common fungal disease of grapes in Indiana, starting out as small brown spots on the fruit that quickly enlarge and cause the berry to rot within a few days. The affected fruit then shrivel and become hard and black "mummies." The fungus also forms lesions on the leaves. The Purdue Plant & Pest Diagnostic Lab has photos and additional information about the disease at http://www.ppdl.purdue.edu/PPDL/weeklypics/Weekly_Picture6-25-01-2.html.

The disease overwinters in the fruit mummies and infected leaves, so cleaning up the planting before winter is critical to preventing the disease the following year. Making sure the plants are properly pruned to allow good light and air penetration will also help prevent disease. There is a window of about 4-5 weeks after bloom when the Concord berries are susceptible to black rot infection. Fungicides applied during this time can help reduce the amount of infection. See Purdue Extension Bulletin ID-146, Managing Pests in Home Fruit Plantings http://extension.entm.purdue.edu/publications/ID-146.pdf.

Q. Is rotted cow manure good for acidifying soil for blueberry plants? We have clay soil and pH is around 5.4. Also, is adding sand a good choice?

A. Blueberries perform best at soil pH of 4.5-5.1, so it would help to bring your pH down a bit more. But composted manure is not likely to change the soil pH significantly, nor is the addition of sand. Peat moss, sulfur and aluminum sulfate are some of the more common products for lower soil pH. When preparing the bed for planting, the best choice is to apply sulfur. For a clay soil, you'll need about 1.5-2 pounds of sulfur per 100 square feet to lower the pH from 5.4 to 5.0. The process is slow, so apply the sulfur at least six months before planting. Recheck the pH before planting to see if additional adjustment is needed. For established blueberry plants, the use of ammonium sulfate as a nitrogen source will help to maintain a lower pH. You'll find more information about fertilizing blueberries in Purdue Extension Bulletin HO-65, Fertilizing Blueberries http://www.hort.purdue.edu/ext/HO-65.pdf.

Q. I have rhubarb plants that never produce. Rather, they always go immediately to seed. Is there something I should be doing so that stalk growth continues until some rhubarb can be harvested from these plants? Also, what in your opinion is the best variety of rhubarb?

A. Some rhubarb plants are more prone to flowering (bolting) than others. Old-fashioned varieties, such as Victoria and MacDonald, are heavy seed stalk producers. Canada Red and Valentine are less likely to bolt. Plant maturity is also a factor, with more mature plants being more likely to bolt than youngsters. Dividing the crowns every 4-5 years should help rejuvenate the planting. Applying moderate amounts of fertilizer, either a balanced fertilizer such as 12-12-12 or well-composted manure, each spring should also discourage bolting.

Weather no doubt has a role to play as well. Rhubarb is a cool-season perennial that can remain productive for 8-15 years, if given proper care. Plant stress, such as temperatures above 90 F, prolonged drought during hot weather, poor nutrition, etc., may also promote bolting.

The bottom line is that rhubarb may bolt for a number -- and likely a combination -- of several factors. Many gardeners may not know what cultivar they have, and there's not much we can do about the weather. So, if your rhubarb bolts, remove the flowering stalks as soon as they are visible, to which the plant will likely respond by sending up another. If you keep at it, the plant will soon return to the desired priority for foliage production. And, if this still does not give satisfactory results, you might consider replacing your current planting with a more dependable cultivar.

 

 

Writer: B. Rosie Lerner
Editor: Olivia Maddox,