FOR RELEASE THE WEEK OF AUG. 30, 1999:
Should I plant new perennials this fall or wait until spring?
Whether "fall is for planting" is an interesting question, says Bob Tripepi, University of Idaho horticulturist. Because the key is ensuring that newly planted herbaceous perennials, shrubs and trees become established quickly, the deciding factor is the climate in which you live.
Climates in which fall weather stays warm enough to allow root growth and establishment before cold temperatures hit are suitable for fall planting. Soil temperatures should be at least 40 degrees Fahrenheit and soil moisture should be adequate for at least a month after planting.
If your fall temperatures are usually moderate and if only a few light frosts typically occur before early October, Tripepi says you can probably plant safely through mid-September. If your climate is warmer and if your fall frosts are fewer, you may be able to extend fall planting through early October. Provide supplemental water, as needed, through late fall.
On the other hand, if you live in an area that has many frosts before early October–some of them in the low 20s or even teens–and if you won’t be irrigating your dry soils, wait until spring to plant perennials. For you, fall is not for planting.
We battle powdery mildew in our yard and garden every year. What, if anything, can we do to prevent it?
Where they’re available, you can plant resistant varieties. Other than that, there’s not much you can do to prevent the airborne disease powdery mildew, says Bob Forster, University of Idaho extension plant pathologist. Once it occurs, however, you can control it with fungicides like Banner, Bayleton, Cleary’s 3366 or elemental sulfur.
Powdery mildew prefers high relative humidity but, unlike most other fungi, its spores can germinate at just 60-70 percent relative humidity and do not require free moisture. Indeed, the leaf-wetting rainfall and overhead irrigation that prompt many other plant diseases actually inhibit germination of powdery mildew spores. Spacing plants far enough apart to allow plenty of air circulation won’t alleviate the threat of powdery mildew, Forster says. "In home garden situations, we see powdery mildew in plants that are all by themselves with nothing around them."
Preventive fungicide applications are a possibility, but they’re not something that Forster generally recommends. "When you see powdery mildew getting started, that’s a good time to spray."
By the way, don’t compost those mildewed leaves. "In theory, if you do it properly, composting will kill the disease spores," says Forster. "But you won’t know if you’ve done that or not, so it’s best to burn them or otherwise dispose of them."
We are trying to put in a new lawn but we can’t seem to kill the purslane. Any advice?
Not only does common purslane produce thousands of tiny little seed, but the succulent leaves of the purplish, low-sprawling weed can reroot themselves after they’ve been hoed. The moisture in the fleshy, cactus-like leaves makes it possible for purslane to successfully reroot even on red-hot summer days, says Don Morishita, University of Idaho extension weed specialist.
New turf seedlings can’t compete against purslane. With or without chemicals, you’ll need to put the heat on it. Morishita recommends the chemical dicamba or the three-way mix trimec–comprised of dicamba, 2,4-D and MCPA.
A nonchemical alternative is solarization: Thoroughly moisten the infested area, then spread clear plastic over it. Clear plastic raises soils to higher temperatures than black plastic because it transfers heat better.
"Leave the plastic in place for at least a week," says Morishita, "That should kill all of the plants and most of the seed."
We have an acreage and plan to buy a few weaned calves this fall. What should we be looking for in their health records?
Check to see if the calves were vaccinated for clostridium, lepto, respiratory complex and–if it’s a problem in your area–redwater, says Kathy Roy, University of Idaho extension educator. Heifers that will be kept for breeding should also have been vaccinated against brucellosis by a licensed veterinarian.
"Work with your veterinarian on designing a continuing vaccination program," she says. "Depending on the type of vaccines used, boosters may be required."
Also check to see if and when the calves were dehorned, castrated, branded and treated for internal or external parasites.
Because the first month after weaning is a stressful time for calves, make sure you start them on a lifelong vitamin and mineral package immediately. According to Roy, those vitamins and minerals will help their immune systems stay strong and fight potential infection.