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Why are my conifers losing foliage?

In the fall, after a long, dry summer, an evergreen conifer may not have enough resources to sustain all of its green foliage; thus, it will shed its oldest foliage (i.e., the foliage found on the innermost part of a branch). In doing so, the tree is prioritizing its resources. The oldest foliage is the least productive because it has become dirty over time and, being on the interior of the branch, receives the least amount of sunlight. The tree will sacrifice this older foliage in favor of the newer, more productive foliage.


Ladd Livingston, Idaho Dept of Lands,

Although the tree’s appearance may be somewhat alarming, this seasonal foliage loss is a normal part of conifer growth. The foliage loss is particularly noticeable in western redcedar, where it is referred to as “flagging.”

Seasonal foliage loss can also be particularly pronounced in pines. Some years seem to have particularly pronounced seasonal dieback, depending on weather patterns and other stress factors. Thus, even when a tree has excessive interior needle loss, it is not necessarily an indicator of disease, insect attack, or other unhealthy conditions. There are some insects and disease agents that tend to attack a tree’s oldest foliage, but these agents usually leave signs of their activity, such as chewing or speckling across the older foliage.

You’ll find more information about seasonal foliage loss here.

Submitted by: Tim Kohlhauff, September 21, 2015


European Chafer

In 2001, European chafer grubs were discovered infesting lawns in New Westminster, the greater Vancouver area of British Columbia, Canada, less than 15 miles from the northernmost border town in Washington State. The risk of movement from infested areas via human activity is high.


Larvae are the damaging stage of the European chafer. They commonly prefer to feed on cereal plants like turf grasses and wheat. They have also been found feeding on the fine roots of broadleaf plants and conifers. In turf, larvae feed in the root zone up to the root crowns. Secondary pests such as raccoons and skunks peel back turf to feed on the grubs, causing significant damage to lawns.

April to May and September to October are the best times to monitor for the grubs because this is when they are the easiest to spot (i.e., at their largest stage).

For more information, see Pest Watch: European Chafer.

Submitted by Sharon Collman, September 14, 2015


Last Call for Tomatoes!

Those of you growing tomatoes should be harvesting them. So how did you do? Did you have lots of red tomatoes, mostly green or very few? Tomatoes can be very temperamental, and, if not cared for correctly, you can end up with few fruit or mostly green tomatoes. Now is the time to write notes about what did and didn’t work in your garden, so you’ll have something to refer to this winter when you’re planning next year’s plantings.


Pick tomato fruits when they reach mature color but still retain some firmness. Size and color will depend on the plant variety selected—yellow, orange, pink, purple, and green varieties exist, as well as the typical red varieties. Tomatoes usually ripen about one month after the fruit begins to show. As the fruits continue to ripen, they will begin to lose firmness, and the flavor may be affected. Tomatoes can be picked early, after the fruit begins to change color, and will continue to ripen off the vine, with best results occurring at temperatures from 68°F to 77°F.

End Uses
Tomatoes are a versatile fruit and can be used in a variety of forms: fresh, frozen, juiced, pickled, stewed, dried, preserved and canned. For details on how to use and store tomato fruit, go to the National Center for Home Food Preservation website, which offers research-based recommendations for most methods of home food preservation. Additionally, see publication PNW300 Canning Tomatoes and Tomato Products.

For more tips on growing tomatoes, see our WSU Fact Sheet FS145E, Vegetables: Growing Tomatoes in Home Gardens.

Submitted by: Gary Fredricks, September 8, 2015


Why Didn’t My Onions form Big Bulbs?

Onions form bulbs in response to day length or the number of hours of daylight. There are two main types of onions: those grown in northern latitudes that bulb in response to long days, and those grown in southern latitudes that bulb in response to short days. The long-day onions grown in Washington will start to bulb when there are 14 hours of daylight. If they are not planted early enough in the spring, bulbing will begin before the plant grows enough to produce a large bulb. When purchasing onion seed, Washington gardeners should be sure to select only long-day onion cultivars.


Big and small onion bulbs

This material is excerpted from the WSU publication Growing Onions in Home Gardens FS097E.

Submitted by: Marianne Ophardt, August 31, 2015


Harvesting Potatoes for Storage

Potatoes that will be stored through the fall and winter should be harvested when mature. Depending on the cultivar, this will be approximately 70 to 120 days after planting.



The vines will start to die back in late summer or early fall, when the tubers are mature. In regions where wet fall weather may hamper harvest, potato plants may be cut off at the soil surface using pruning shears. Stop irrigating after the tops die back naturally or you cut them off. This promotes wound healing and tuber maturation.

Dig your potatoes approximately 2 weeks after the vines have died back or been cut back. Waiting allows the skin to thicken, so they will not injure as easily when dug.

This material is excerpted from the WSU publication Growing Potatoes in Home Gardens FS118E

Submitted by: Marianne Ophardt, August 24 2015


2015 Winter Damage to Evergreens: East of the Cascades

Early Fall 2014 proved to be unseasonably warm and dry east of the Cascades. Plant respiration continued at a higher rate than normal for this time of year and, in many cases, irrigation was winterized. This meant that some evergreens were unusually water stressed. The warm and dry fall was followed by unseasonably low temperatures in November. This unusually hard freeze, coupled with the drought stress, meant that many evergreens suffered tissue damage.

Some of the plants seen with winter cold damage are dwarf arborvitae, hinoki cypress, boxwood and ponderosa pine.

Fig 1

Figure 1. Dwarf arborvitae leaf and twig winter cold damage, ranging from leaf necrosis to branch dieback.

Fig 2

Figure 2. Hinoki cypress suffering complete winter kill


While leaf necrosis and branch dieback can be unsightly, most of the plants with this winter cold damage will survive. If the leaf buds were not damaged the plant will grow out of the problem. It is important to wait until late spring or early summer to determine the full extent of the damage.

Fig 3

Figure 3. Boxwood showing leaf and twig winter cold damage along specific areas of the plant, such as the top or side.

Fig 4

Figure 4. Ponderosa pine needle winter cold damage ranges from minor needle tip damage to, in severe cases, complete needle necrosis.




Prune out dead branches to clean up plants. Let the new growth expand and grow to fill in void areas. Careful pruning over the next few years will usually bring back the normal healthy appearance of the plant. If branch dieback goes into the dead zone of conifers, the plant many not return to its original appearance and will need to be replaced.

Submitted by: Paula Dinius, August 13, 2015


Do woody mulches attract termites, carpenter ants, and other pests?

Many wood-based mulches are not attractive to pest insects but are actually insect repellent. For instance, cedar (Thuja) species produce thujone, which repels clothes moths, cockroaches, termites, carpet beetles, Argentine ants, and odorous house ants. In general, termites prefer higher nutrient woody materials such as cardboard, rather than wood chips.

Courtesy Wikipedia

Termites – courtesy Wikipedia

For more information on wood chip mulches, see “Using Arborist Wood Chips As a Landscape Mulch” WSU Extension Fact Sheet FS160E.

Submitted by: Linda Chalker-Scott, August 10, 2015


My squash plants are blooming, but no fruit has set. Why not?

For most squashes, the male and the female flowers (distinguished by the round chamber at the base of the flower) are on the same plant. These flowers are dependent on honey bees and other bees to transfer the male pollen to the female flower. Take precautions to minimize insecticide use during flower bloom and encourage bee access and visitation. Inadequately-pollinated female squash flowers may grow, but abort before full fruit development.

1 2
Female and male flowers (Rasbak, Wikimedia Commons)

For more information on how to grow squash in your home garden, see WSU Extension Factsheet FS087E “Growing Squash in Home Gardens.”

Submitted by: Sheila Gray, July 20, 2015


Is wood chip mulch a fire hazard?

Coarse textured organic mulches, like wood chips, are the least flammable of the organic mulches. Fine textured mulches are more likely to combust, and rubber mulch is the most hazardous of all tested landscape mulches. If organic mulches are kept moist, they are less likely to catch fire. If you use flamers for weed control in areas near wood chips, be sure to soak the mulched area first.

arborist chips 2
Photo credit: Linda Chalker-Scott

For more information on wood chip mulches, see “Using Arborist Wood Chips As a Landscape Mulch” WSU Extension Fact Sheet FS160E Publications/FS160E

Submitted by: Linda Chalker-Scott, July 20, 2015


When is my garlic ready to harvest?

After the leaves on the lower third of the plant have turned yellow, garlic is ready to harvest. This usually occurs during late June and mid-July depending on the growing climate and the garlic variety planted. Be careful not to damage the bulb during harvest—any wounds or bruises make the bulb more susceptible to disease and deterioration during storage. Use a trowel or spade to gently loosen the soil under the bulb. Remove any soil from the bulb and its roots gently. Place the garlic with the tops intact in a dry, cool, well- ventilated place to cure. Store in mesh bags, braided, or in hanging bunches. After several weeks, the garlic will be cured. To prepare the garlic for use, cut the tops to roughly 1 inch and trim the roots. After curing, the garlic will keep for several months.


Photo credit: Linda Chalker-Scott

For more information on how to grow garlic in your home garden, see WSU Extension Factsheet FS162E, “Growing Garlic in Home Gardens

Submitted by: Sheila Gray, July 13, 2015


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