Acorn Crop Very Light This Year

Oaks are among the most common hardwood tree species in many parts of Virginia.  Because of their importance both as a source of forest regeneration and as a mast crop for wildlife, each year’s acorn crop is the subject of much attention.  Many reports from various parts of the Commonwealth indicate that the acorn crop this fall is very light, according to officials at the Virginia Department of Forestry (VDOF) and the Virginia Department of Game and Inland Fisheries (DGIF).

VDOF Research Program Manager Jerre Creighton said, “Acorn production varies widely – from nearly zero to a quarter million or more acorns per acre. Different locations, years, species and even individual trees produce extremely different crops, and heavy ‘bumper’ crops occur only every two to seven years.”

Many factors – such as weather, insects and disease – that collectively influence acorn development from the time of flower initiation to acorn maturity.

Late spring freezes and high humidity during pollination are primary causes (we experienced both of these over much of Virginia in 2013).  In addition, research has shown that the inherent cycles between bumper crops and light crops may be an adaptation to allow the trees to restore their resources following a bumper crop.

Creighton said, “In other words, a large crop one year may reduce the trees’ resources resulting in lower production the following year(s). Since 2012 was a bumper crop of acorns for much of Virginia, this could be another explanation for this year’s light crop.  The overall consensus seems to be that there are inherent cycles of reproduction that are modified by the impact of weather conditions in a particular location.”

Gary Norman of DGIF said, “Acorn production in Virginia in 2013 was low – comparable to the previous low in 2008.  The white oak crop appeared to uniformly fail across the state, while some pockets (generally in eastern Virginia) of good red oak production were found.  Mast production has alternated from high to low levels since 2010. The impacts of acorns on wildlife populations are extensive and complex.  And they are most dramatic where there is little diversity of habitat types and few alternative food sources to acorns.”

DGIF officials are concerned about a light crop because acorns are a preferred food for many wildlife species, including white-tailed deer, black bear and wild turkey.  Acorns are rich in fat, soluble carbohydrates and energy, which are important nutritional needs that contribute to the animal’s body condition, survival, harvest rates, reproduction and, eventually, population status.  The roaming range of black bear and wild turkey can increase two- to four-fold in years with mast failures, and long-range gray squirrel movement can be significant as they search for acorns.

Norman said, “Oftentimes the search for food creates situations that bring wildlife closer into residential areas to find human-related food sources resulting in unwanted interactions between animals and people.”

Forests and Fall Migration

At this time of year, Virginia’s forests are changing in ways beyond the obvious fall color display. Forest dwellers are changing their seasonal habits as well. Birds and waterfowl, noticing the drop in temperature, shorter days and dwindling food supply, are beginning their annual migration.

A streamside forest is a great place to observe birds and waterfowl migrating from September through January. Follow the trails along rivers, streams and forested shorelines. These riparian buffer zones, with habitat and food for a variety of ducks and birds, are great places to watch the activity.

Migratory species require frequent meals to sustain their energy. Favorite foods include insects, small fish, fruits, small nuts and seeds.

Migrating finch are on the lookout for small seeds. River Birch, Sycamore, Sweet Gum, Cottonwood Poplar and pines all have smaller, nutrient-rich seeds to boost the energy level of migratory species. Turkeys scour for acorns. After a frost, fruits such as soft persimmons, holly berries and dogwood berries have high sugar content, making them a good migratory snack. Some fruits remain on trees throughout the winter, providing forage for the year-round residents that don’t migrate, such as cardinals.

To learn more about migratory species that frequent and live in riparian forests along waterways visit the following websites:

Cornell Lab of Ornithology www.birds.cornell.edu 
http://Nationalzoo.si.edu
http://www.audubon.org
http://www.dgif.virginia.gov

Find Fall Color Off The Beaten Path

Visitors come from near and far to admire Virginia’s autumn splendor. Some of our foresters have developed local scenic driving tours as an alternative to well-known, and well-traveled, locations.

The self-guided driving directions offer spectacular views in some of our most picturesque countryside. Scenic driving tours are listed for the following areas:

• Charlottesville and Culpeper Area: counties of Greene and Madison
• Harrisonburg area: counties of Rockingham and Shenandoah
• Lexington area: Bath County
• Roanoke area: counties of Bedford, Craig and Franklin
• Staunton area: Highland County

To learn more about the fall foliage season in Virginia, and access or print driving directions, visit dof.virginia.gov/fall/.

Fall Fire Season Now Underway

As temperatures begin to dip and the leaves on the trees begin to change color, it’s time once again for the start of fall wildfire season in the Commonwealth. Officials at the Virginia Department of Forestry (VDOF) remind all Virginians that the threat of wildfire increases each autumn as leaves dry out and fall from trees, grasses turn brown, humidity levels drop and winds increase.

“Wildfires are directly linked to weather conditions,” said John Miller, director of resource protection at VDOF. “Whether it’s someone burning debris or trash, an unattended campfire or an intentional case of arson, wildfires have a greater chance of causing bodily harm or property damage in the fall and spring months because the conditions are right for fires to burn hotter and spread faster.”

Each year, Virginia experiences more than 1,200 wildfires that burn more than 10,000 acres of land. VDOF employees annually protect hundreds of homes from the ravages of wildfires, but each year there are always some homes that are destroyed by these wildfires.

Miller said, “Since more than 95 percent of wildfires that occur in Virginia are the result of human activity, taking even the simplest precautions with outdoor fires will significantly reduce the occurrence of wildfires and the threat to you and your neighbors.”

Fall Fire Season runs annually from October 15 to November 30.

VDOF Working to Plant Trees on Open Lands

As part of its Open Lands Tree Planting Initiative, the Virginia Department of Forestry has hired a mapping and outreach specialist to work out of the Mecklenburg County Forestry Office. Tim Minich will analyze land-use data from multiple sources, identify appropriate land for tree planting and conduct some field forestry work in one of three outreach focus areas of the Commonwealth.

The Open Lands Tree Planting Initiative is designed to prevent the loss of forestland; increase the sustainability of the forest resource, and improve water quality and diminished species concerns. The strategies to tackle these issues are to: promote and enhance forested watersheds; improve stewardship, health, diversity of forest products, and conserve the forestland base.

Senior Area Forester Adam Smith said, “The opportunities to consider in the open land outreach are to increase forests and benefits; plant pine in the more than 71,000 acres each year that revert back to a natural forest, and to overcome the natural reversion of forest stands that are under stocked with undesirable species.”

Minich will be working with area VDOF employees who have local knowledge and extensive county contacts, along with partner agencies, such as the Soil and Water Conservation District, the Natural Resources Conservation Service, the Farm Service Agency and Virginia Cooperative Extension. He will send letters to land owners, conduct presentations for community groups and develop landowner workshop opportunities.

Minich said, “The state target goals will be 200 new sites and more than 2,000 acres of open land on which to plant.”

Smith said, “We are confident the additional outreach efforts will pay great dividends. The Virginia Department of Forestry will provide the tools and the manpower to assist any interested landowner with available cost-share funds from state and federal sources. It is a win, win situation for all.”

Minich will focus his efforts in the counties of Mecklenburg, Lunenburg and Brunswick but will also do some work in the counties of Prince George, Sussex, Surry, Isle of Wight, Greensville, Southampton and the City of Suffolk.

To learn more about the Open Lands Tree Planting Initiative or to contact Tim Minich, please call 434.738.6123.

Southwest Virginia Residents Starting to See Widespread Decline of Hemlocks

Hemlock trees are an important component of the forests in southwest Virginia, but they are under attack by a tiny insect capable of killing the trees, according to officials with the Virginia Department of Forestry.

While not a major timber species, hemlock trees have numerous environmental benefits due to their high tolerance for shade. Hemlocks grow particularly well along stream sides and moist cove habitats, providing deep shade that helps moderate temperatures, enhances habitat for fish and wildlife, and increases overall biodiversity.

Senior Area Forester Bill Miller said, “The tiny, aphid-like insect called the hemlock woolly adelgid (HWA), which is an invasive species from Asia, poses a major threat to the hemlock resource.”

Accidentally introduced to Richmond, Va., in 1951, the insect has since spread throughout the entire native range of hemlock within the Commonwealth. However, despite its presence in Virginia for more than 60 years, it took most of that time to reach the southwestern Virginia counties bordering Kentucky and Tennessee, where it’s been known for only the last five to 10 years. New county records for the hemlock woolly adelgid were established for Russell and Tazewell in 2005; Buchanan, Dickenson, Wise and Lee in 2006, and Scott in 2007.

VDOF Forest Health Specialist Dr. Chris Asaro said, “Hemlock woolly adelgids are immobile after finding a suitable place on the tree to feed. They insert their straw-like mouthparts into the terminal ends of hemlock branches, sucking sap and producing a white, waxy coating over their bodies, which looks something like tiny balls of cotton. Adult female hemlock woolly adelgids also lay their eggs within this protective wax. Most people never observe the actual insects, but are more likely to see these tiny white balls of wax scattered around the underside of twigs and terminal branches.”

While many species of insects suck sap in this way and are mostly harmless, HWA is unique in that its saliva is toxic to eastern hemlocks in North America, according to Dr. Asaro. Thus, their feeding causes localized tissue damage and death, which spreads from twigs to branches and, ultimately, to the entire tree. This process of decline and death from their feeding will often occur within five years of initial attack. However, this is highly variable, and many hemlock trees infested with HWA have survived for many more years without showing symptoms of severe decline. Scientists still don’t fully understand what factors dictate this variability; but older, larger trees seem to succumb more quickly than mid-sized trees and saplings, at least in some locations.

Increasingly, homeowners and landowners across southwest Virginia are becoming more aware that something is wrong with their hemlocks, but may not understand the cause. However, once identification of HWA occurs, there are some control options available. While it’s true that hemlocks will likely continue to decline and die in many forested locations, it is also possible for homeowners to protect their ornamental hemlocks using a variety of products available over-the-counter.

Miller said, “For smaller trees in which all parts of the tree are easily reached, insecticidal soaps or horticultural oils are quite effective, and are relatively safe to use and easy to apply. The down side is that they wash off fairly regularly and have to be reapplied with greater frequency, especially the soaps. Soaps, however, are extremely safe to handle and are relatively non-toxic. Oils are slightly more toxic than soaps but don’t have to be reapplied as frequently. Both are fairly inexpensive.”

For protection of larger trees, systemic insecticides that can be applied to the soil and root zone are available. Systemic insecticides are taken up by the tree through the roots over several months until the product is circulated through the entire tree.

Dr. Asaro said, “This can sometimes take up to six months depending on tree size and other factors, so it should be applied before trees start to decline significantly. Systemic insecticides work best if applied in the springtime. If too much of the crown is already killed, uptake of the insecticide will be poor.”

These products are considered easy to use but are more expensive. However, one application to the soil usually affords two to three years of protection to the tree before it needs to be reapplied.

Dr. Asaro said, “These systemic products should not be used near water or in areas with a high water table, or near trees or crops that are pollinated by insects. Follow all pesticide label directions exactly; the label is the law.”

Homeowners should be aware of their options for protecting their hemlock trees. Unfortunately, HWA is becoming a fact of life for this area and will no doubt impact many landowners negatively. For more information about HWA, please contact your local Virginia Department of Forestry or Virginia Cooperative Extension office.

Scattered yellow-poplar decline reported across Lee, Wise and Scott counties

Recent declines in yellow-poplar in Lee, Wise and Scott counties have landowners concerned over the health of one of the most abundant and resilient hardwood trees in Virginia’s forests. While not entirely certain about the reason for the declines, Virginia Department of Forestry personnel believe they may stem from past insect infestations that previously went unnoticed.

Yellow-poplar, or tulip poplar, is the most common hardwood tree in Virginia and one of the most important timber species in far southwest Virginia. Its rapid growth, straight trunk and wood properties, along with its abundance, make it an excellent tree for loggers to harvest in bulk and bring to the mills. Generally speaking, yellow-poplar is a resilient tree that does particularly well in moist cove habitats and fertile soils common to the lower slopes and valleys of the southern Appalachians. It also has very few insect and disease problems due to the fact that the leaves, bark and wood contain a host of chemicals that deter them. Even an invasive species like the gypsy moth, which can feed on more than 200 species of trees and shrubs, will completely avoid feeding on yellow-poplar.

“Two notable exceptions to this rule, however, are native insects known as the tulip tree scale and the poplar weevil,” said Bill Miller, senior area forester with the Virginia Department of Forestry. “The scale is a tiny sap-sucking insect that produces a brown, waxy covering that looks something like a tortoise shell. Populations of these insects can occasionally reach such high levels in the forest that they can damage and even kill poplar trees, although this is rarely seen in southwest Virginia.”

On the other hand, the poplar weevil is a defoliating insect that is particularly common in southwest Virginia, especially in Lee, Scott, Wise, Dickenson, Buchanan, Russell and Washington counties, along with adjacent counties in Kentucky and Tennessee. In most of these counties, as many as six to eight poplar weevil outbreaks have been documented over the last 25 years by forest health personnel with the Virginia Department of Forestry. Feeding by individual weevils in spring causes little damage to newly emerged leaves, other than a small brown patch. During outbreaks, however, millions of weevils can result in poplar trees being heavily defoliated. These outbreaks are often patchy in nature but can span large areas.

VDOF Forest Health Specialist Dr. Chris Asaro said, “While the word ‘outbreak’ can sound very dramatic, the truth is that these defoliation events are often not noticed from the ground for several reasons: they are very patchy across the landscape and often occur in remote areas that are not easily visible. In addition, poplar trees are generally quite tall and most people driving by don’t have the tendency to look up. Furthermore, while complete defoliation of poplar can occasionally occur, trees with adequate moisture often leaf out again pretty quickly, erasing any evidence of past damage. Outbreaks typically don’t last very long in any one area either because poplar weevil has a host of other insects that prey on them, which usually causes outbreak populations to crash after a year or two.”

While one defoliation event by itself is probably not going to cause poplars to decline or die, several defoliation events over successive years can weaken trees and, combined with other stressors such as drought, lead to some localized dieback, decline or even death. Recently, some landowners across Lee, Wise and Scott counties have seen such poplar decline over the last few years and have expressed concerns to local foresters. In most cases, these areas of decline are small – generally from ½ acre to several acres in size – although several locations have exhibited decline spanning 50 acres to 100 acres.

“There appears to be no obvious reason why these declines show up where they do, other than the fact that these areas were known to have several weevil outbreaks during past years,” Asaro said.

“Because tree decline is a gradual process that can take many years and be caused by multiple agents, it’s always difficult to pinpoint exact causes. But knowing that the weevil is a major presence in the region and one of the few insects that can feed on poplar, it seems very possible that it is playing a prominent role in these decline events,” Asaro said.

The good news is that the affected areas are quite small, and most of the poplar trees are weakened but not dead. That means the wood is probably still sound and can be salvaged, so most landowners can still profit from forests with some poplar decline. Forest landowners concerned about their poplar stands should consult their local Virginia Department of Forestry office for further information and advice.