UC Gardening Blogs

Foraging Bumble Bees: Check Out the Orange Pollen

Bring on the bumble bees! In yesterday's Bug Squad blog, we mentioned the unusual...

A yellow-faced bumble bees, Bombus vosnesenskii, nectaring on rosemary at the Benicia Marina on New Year's Day, 2018. Note the orange pollen, derived from another floral species, probably California golden poppies. (Photo by Kathy Keatley Garvey)

The yellow-faced bumble bee, Bombus vosnesenskii, heads for another rosemary blossom at the Benicia Marina. (Photo by Kathy Keatley Garvey)

The yellow-faced bumble bee, Bombus vosnesenskii, heads for another rosemary blossom at the Benicia Marina. (Photo by Kathy Keatley Garvey)

Peek-a-bee! The foraging bumble bee, Bombus vosnesenskii, displays a little of its orange pollen. (Photo by Kathy Keatley Garvey)

Peek-a-bee! The foraging bumble bee, Bombus vosnesenskii, displays a little of its orange pollen. (Photo by Kathy Keatley Garvey)

Posted on Tuesday, January 2, 2018 at 4:59 PM

Author: Kathy Keatley Garvey

Rodenticides: Use, Issues, and Nontarget Exposure

[From the Winter 2017 issue of the UC IPM Green Bulletin] Rodenticides are essential tools in...

Posted on Tuesday, January 2, 2018 at 12:43 PM

Author: Niamh Quinn

Black Knot Disease

Many years ago my dad planted a Santa Rosa plum in his backyard in Modesto. Every year it abundantly produced delectably sweet, juicy yellow plums, that we all enjoyed. This summer, however, he was only able to find about a dozen to pick. He took a good look at the tree and started his online search for pictures that appeared to be what was wrong with his tree. His conclusion is that his beautiful tree has Black Knot Disease. The cause is a fungus called Apiosporina morbosa also known as Dibotryon morbosum. It attacks trees and shrubs in the Prunus family - plums, chokecherries and some cherries, not so much peaches or apricots. There are cultivars that are resistant or at least not as susceptible. Santa Rosa plums are listed in this category.

Black Knot Disease is most commonly detected in winter, when the leaves have fallen from the tree. The disease first appears as soft, green growths on twigs and branches at sites of leaf attachment. These turn brown, harden and enlarge eventually turning black. By this time, the tumor is often large enough to encircle the twig or limb causing it to die. Old knots can also be attacked by boring insects or by the fungal parasite Trichothecium roseum, which can cause the black knot to turn white or even pink.

The disease does not occur in one season. The fungus spends the winter in knots or weakened areas around the knots on the tree's branches or twigs. Come spring, spores are produced on the knot's surface in sacs. When rain arrives, the spores are shot into the air and carried by the wind to twigs of the new season's growth. If the twig stays wet for a long enough period, the spores germinate and infect the twig. The new green twigs are the only part of the tree susceptible to infection by this spore. The fungus grows during the cool weather in the infected wood enlarging each year. When it is finally noticed, the treatment is to cut the branch 6 to 8 inches below the knot, disinfecting the tool between cuts. This is usually done in the spring. Even with removing what is noticeable, it can take another year or two to effectively cut off all the diseased areas. What has been cut off should be removed from the area, and not dumped in the green can. The spores on the prunings can survive for several weeks. Fungicides are not cures on their own, so they are not recommended.

This fungus is native to North America, but it is most often seen in the Northeast. It is also commonly found in the South and Southeast and in the Midwest. How it got to my dad's tree in Modesto is any one's guess. What is not a guess - this tree is a goner. One of the tumors has almost encircled the trunk. My dad plans to have his beautiful tree cut down soon.

photos by Michelle Davis

black knot 2

Posted on Tuesday, January 2, 2018 at 7:11 AM

Author: Michelle Davis

Celebrating the New Year with Bumble Bees in Benicia

While folks from Alaska to Colorado to New York to Maine are shivering in freezing temperatures,...

A yellow-faced bumble bee, Bombus vosnesenskii, forages on New Year's Day, 2017, on jade at the Benicia Capitol State Historic Park. (Photo by Kathy Keatley Garvey)

A yellow-faced bumble bee, Bombus vosnesenskii, forages on New Year's Day, 2017, on jade at the Benicia Capitol State Historic Park. (Photo by Kathy Keatley Garvey)

Check out the cream-colored pollen on this yellow-faced bumble bees, Bombus vosnesenskii, nectaring today (Jan. 1) on jade at the Benicia Capitol State Historic Park. (Photo by Kathy Keatley Garvey)

Check out the cream-colored pollen on this yellow-faced bumble bees, Bombus vosnesenskii, nectaring today (Jan. 1) on jade at the Benicia Capitol State Historic Park. (Photo by Kathy Keatley Garvey)

Bottoms up! A yellow-faced bumble bee, Bombus vosnesenskii, dips for nectar on a jade blossom in Benicia. (Photo by Kathy Keatley Garvey)

Bottoms up! A yellow-faced bumble bee, Bombus vosnesenskii, dips for nectar on a jade blossom in Benicia. (Photo by Kathy Keatley Garvey)

Posted on Monday, January 1, 2018 at 3:04 PM

Author: Kathy Keatley Garvey

The Gardens at the Tusayan Ruins in Grand Canyon National Park, Arizona

I recently returned from a trip to the Grand Canyon. Although there are many wondrous and marvelous things to see at the Grand Canyon National Park, this blog entry will focus on the Tusayan Ruins located within the park because of the grounds and garden there.

The Tusayan Ruins (pronounced "Two-see-yawn") at the Grand Canyon Park, consists of a Native American pueblo dating back to the 1100's. According to the park ranger who spoke on the tour I attended, he said that no one is certain of the origin of the term, "Tusayan." The Native Americans who lived in this pueblo prior to relocating from it (for reasons unknown), did not refer themselves as such. Instead, the term was the Spanish name for this geographical area where the pueblo is located, and archaeologists in the 1930's who were excavating the area, adopted the usage of that term for the Native American tribe that lived in this place.

Although the ruins are interesting because they give visitors an idea of how this particular tribe lived (they hunted, gathered, and engaged in small-scale agriculture), for our purposes, we will look to the gardens cultivated by this tribe. According to the park ranger who led the tour and the artifacts displayed at the on-site museum, the primary crops grown by this tribe were the Three Sisters--corn, beans and squash. In addition, the tribe cultivated the pinon tree from where they would harvest pine nuts, use the sap to waterproof their baskets, and used the timber to construct their living quarters. They used sagebrush for dye and for cleansing ceremonies and grew Mormon tea so that they could have tea.

I was impressed at the resourcefulness of this tribe and their way of life. If your journeys take you to the Grand Canyon, it is a worthwhile stop to see the Tusayan Ruins.

photos by Betty Homer