January 2011 Gardening Q&A

by B. Rosie Lerner
Purdue Extension Consumer Horticulturist

Pre-emergent herbicide can help reduce weed in yard

Q: During this past summer’s drought, crabgrass took over our yard. Is there an effective way now to get rid of it, or has it already seeded itself for the spring? Now that it’s turned brown, would going out and pulling it up by the root do any good? — BAB, Avon, Ind., via e-mail

A: Crabgrass is an annual plant, meaning it only lives for one growing season. The plants flower and produce seed in July, then die at first frost. So there is not much point in pulling the plants out now. Unfortunately, crabgrass produces a lot of seed in summer that will then germinate next spring. Crabgrass is a really tough weed to completely eradicate, and it thrives in poor, sparse turf. The best strategy is to prevent the crabgrass as much as possible. Good lawn care practices, including appropriate fertilizing, watering and mowing, will help the turf grass be more competitive.

A pre-emergence herbicide applied in early spring before the crabgrass germinates can substantially reduce the population next season. In central Indiana, you would need to apply by early April most years. For more information on crabgrass control in home lawns, see Purdue Agronomy publication AY-10-W at http://www.agry.purdue.edu/turf/pubs/AY-10.pdf.

Q: For the last two years my Nandina has produced a lot of flowers that promised to berry, but the berries seem to drop off before fruition. It has berried beautifully in the past, and there has been no change in environment. — Vicki Meredith, Lanesville, Ind.

A: Nandina is marginally hardy to southern Indiana, but it is considered to be an invasive, weedy species in the southeastern United States where it forms vigorous spreading colonies. Although commonly called heavenly bamboo, it is not a bamboo but rather a member of the barberry family. There are quite a few cultivars in commerce that vary in plant size, foliage, flower and fruit color. Generally, the plant flowers in May or June and the fruits ripen in September or October.

The individual flowers have both male and female parts present; however, fruit set is improved when there is more than one plant. Some cultivars have been selected for lack of fruiting in an effort to decrease invasiveness. But since your planting used to produce fruit, is it possible that you had more than one plant in the past? Also, pruning after flowering would remove the potential for fruit.

Q: I have some black-eyed Susans. How do they reseed themselves? I know that wherever you plant them they take over everything. — Carl Bentley, via e-mail

A: Rudbeckia, aka black-eyed Susan, are bountiful self-seeders. Depending on the perspective of the individual gardener, this may or may not be a good thing! The seeds mature as the flowers fade and either fall to the ground or are distributed by the many birds that enjoy the snack. If you prefer to reduce the amount of self-seeding, remove the spent flowers — referred to as deadheading — just as soon as the petals fade. The plants will look better, and preventing seed production will also encourage additional blooms.

Q: My Concord grapes used to get ripe all at the same time. Now, the last two years, they don’t. They all ripen unevenly; some are green, some are ripe and some are over ripe or starting to rot on the same bunch of grapes. What is my problem? — Daniel Wendholt, Huntingburg, Ind.

A: Some grape-growers have experienced uneven ripening this year, particularly with their Concord grapes, and this seems to be an issue when the weather has been exceptionally warm. Some of the berries in the cluster remain sour, hard and green while others develop the purple color and soften during the ripening process. The green berries will be full-sized, but will not be sweet. For some reason, those berries never go through the increase in sugar and decrease in acids that commonly occurs during fruit ripening. It is not clearly understood why this phenomenon occurs, but hot weather is thought to be partly responsible. So let’s hope for better weather next year.

And here is a great story from one of our readers!

Your story about white pines in the September issue of Electric Consumer inspired me to tell about the “miracle pines” growing in our yard.

In 1981 we planted 24 white pines. The neighbor’s bull destroyed two of them when they were about 8 feet tall. The other 22 are still living and the tallest is about 40 feet high. One is 23-inches in diameter at the base of the trunk. For 20 years or so I plucked a lot of bagworms off of them, but that is all the special care they have received.

Evidently, they have lived three life expectancies and still look healthy, so I refer to them as our “miracle pines.” We planted more white pines in 1994, which have not fared as well as the others. So far, we have lost two of them to pine bark beetles and sap suckers.

We are hoping they continue to flourish. However, if they should all die I am considering leaving the dead trees standing and placing a “Welcome to Dead Pine Acres” sign at the entrance to our property. That sounds much simpler than dealing with pine sap on saw blades. — Leo Arvin, Loogootee, Ind.