Treesearch

Field inoculation trials are an important component of screening American elms (Ulmus americana) for levels of resistance to Dutch elm disease. A major concern in screening is variability in disease ratings from year to year. Previous studies have demonstrated that timing of inoculation can have a significant impact on disease susceptibility. In this study, trees were inoculated in the main stem using a drill method of inoculation. A recently collected isolate of Ophiostoma novo-ulmi with known pathogenicity was used for inoculations. Three different inoculation times were examined: early...

A variety of methods have been used by different research groups to "challenge" inoculate American elms (Ulmus americana) with the purpose of determining whether some clones may be resistant to the Dutch elm disease fungus. The methods used by seven research groups are described, along with observations on complications and benefits associated with each. The response of test trees to challenge is affected by many factors, including the age of parent material, size/maturity of test material, vigor of the plant being inoculated, portion of the plant inoculated, season/time of year, source of...

We report a case study that demonstrates the successful use of the fungicide Arbotect® 20-S to protect American elms (Ulmus americana) from Dutch elm disease at a historic site in Charleston, WV. Standard injection protocols were used every 3 to 4 years to deliver the chemical into the root flares. Twelve of the original 16 trees remain 34 years after the initial treatment.

In North America, American elms were historically present throughout the northeastern United States and southeastern Canada. The longevity of these trees, their resistance to the harsh urban environment, and their aesthetics led to their wide use in landscaping and streetscaping over several decades. American elms were one of most cultivated plants in the United States until the arrival of Dutch elm disease (DED) and elm yellows disease (EY). EY epidemics have killed large numbers of elm trees in the northeastern United States beginning in the 1940s. Since then, the disease has gradually...

The elm yellows phytoplasma (Candidatus Phytoplasma ulmi) is a geographically widespread pathogen that poses a significant threat to most native wild elms in North America (Ulmus americana, U. rubra, U. alata, U. crassifolia, and U. serotina) (Mäurer et al. 1993), as well as to the success of American elm research programs focused on breeding Dutch elm disease tolerance. Despite the advancements of American elm research programs in creating Dutch elm disease-tolerant varieties, elm yellows research has lagged and threatens to undermine the success of breeding programs. Here, we have three...

Before Dutch elm disease, the American elm (Ulmus americana L.) was a leading dominant tree species in the better drained parts of floodplain forests where flooding occurs about 1 percent of the time. Although still common in these habitats today, U. americana now rarely lives long enough to reach the forest canopy because elm mortality rates increase sharply with tree size. This article reviews the impact that the loss of American elm due to Dutch elm disease on floodplain forests, helps provide a clear rationale for restoring this iconic species in the wild, and also provides quantitative...

The impact of Dutch elm disease (DED) on the genetic diversity of slippery elm (Ulmus rubra) is summarized and its potential impact on the genetic diversity of other North American native elms, American elm (U. americana), rock elm (U. thomasii), winged elm (U. alata), cedar elm (U. crassifolia), and September elm (U. serotina), is discussed. The potential for hybridization between the introduced Siberian elm U. pumila and the native North American elms is considered given previous findings with U. rubra. We do not expect DED to reduce the genetic diversity of these native elms. The only...

We present the background and characteristics of American elm clones that are commercially available or of interest in research on Dutch elm disease (DED) tolerance in the United States. The characteristics of interest include origin, ploidy level, whether available in nursery trade, evidence of DED tolerance, and other comments. The list includes 10 named commercially available cultivars, six additional named American elms of interest, and six numbered clones of interest.

It is generally assumed that severe disturbances predispose damaged forests to high fire hazard by creating heavy fuel loading conditions. Of special concern is the perception that surface fuel loadings become high as recently killed trees deposit foliage and woody material on the ground and that these high fuel loadings may cause abnormally severe fires. This study evaluated effects of severe, exogenous disturbance events, namely fire and beetles, on future fuel conditions through biannual field collections. We measured surface fuel deposition and accumulation rates for a number of forest...

Wind erosion of soils burned by wildfire contributes substantial particulate matter (PM) in the form of dust to the atmosphere, but the magnitude of this dust source is largely unknown. It is important to accurately quantify dust emissions because they can impact human health, degrade visibility, exacerbate dust-on-snow issues (including snowmelt timing, snow chemistry, and avalanche danger), and affect ecological and biogeochemical cycles, precipitation regimes, and the Earth’s radiation budget. We used a novel modeling approach in which local-scale winds were used to drive a high-resoluti...