Editor's note: Master Gardeners are keeping busy in their own gardens during Napa County's “Shelter in Place” directive. It's spring, it's getting warmer, it's a great time to work in the garden! Here's how Master Gardeners are spending their time:

by Dianne Weyna

One of the first warm days this spring I decided to go crazy pulling weeds, knowing it was going to rain later. I wanted to “nip it in the bud,” so to speak.  Removing weeds before they spread their seed is the goal. It's interesting how weeds have different strategies for seed dispersal. 

I have a lot of little bittercress Cardamine oligosperma in my yard.  This is a small plant with leaves formed in a basal rosette, a long stem and usually a little white flower on the end.  I look for the little flower and pull, hopefully by the root.  I have lots of them that need to be removed before they annoyingly disperse their seed by ballistic projection. This method of seed dispersal is also used by creeping wood sorrel Oxalis cornicalata that looks like clover or oxalis, but is smaller with yellow flowers.  Pulling the weeds while green can prevent up to dozens of seeds from shooting out. A tension between dry outer cells and moist inner cells causes the “explosion” when the seed pods are ripe and turning yellowish to brown.  It doesn't seem to matter how small the plant is; they still produce seed.  It's easy to miss them. I'm not sure if this is the weed's idea, but it works.

The other weed I'm trying to discourage is the dandelion Taraxacum officinalis.  We all know the dandelion, and I often just try to pick the yellow flowers before they become the big ball of seeds just waiting for a small wind gust to disperse them.

Buttercup oxalis - Oxalis pes-capres, is another plant that is all over my garden.  They reproduce by bulbs and bulblets.  It's hard to remove them all by pulling, and it doesn't really stop their spread, but the above ground material works well for the green part of compost.

Catchweed or Bedstraw Galium aparine is a weed with an interesting reproduction plan: its transfers its seed to us or other mammals by using little hairs with hooks on the end that clings to our clothes (or fur) like a burr. The plant itself also has these hairs and feels sticky, but the unwelcome feeling is just the hairs. 

We have a lot of spare time to do the weed picking this year, but I try not to clean out my gardens too quickly because the birds need the seeds for food and the sticks and dried vegetation for nest building. I am seeing lots of birds in my garden, such as bush tits I hadn't noticed before, along with Wilson's warbler and Allen's hummingbird!

Another thing that I love to see are old pods from flowers of last summer.  Poppy pods are beautiful, some totally skeletonized, showing architecture of the pod.  I have seen skeletonized leaves, too, mostly citrus, and they're beautiful. 

The western grape leaf skeletonizer and the palm leaf skeletonizer can cause extreme damage to local grape crops and palms. These are not the insects that make the delicate lace-like leaves; the damage they cause looks more like blotches on the leaves. But, fortunately we do no yet have either of these pests in Napa County. If you think you have seen either of these invasive pests on your plants contact the Napa County Agricultural Commissioners office. And if you are able, bring in a sample of the insect or damage for them to identify. "

Life is an adventure…. Enjoy your garden!

 

 

Informational links:

UCANR Weeds ID & info http://ipm.ucanr.edu/PMG/weeds_all.html

Western grape leaf skeletonizer info http://ipm.ucanr.edu/PMG/r302301011.html

Palm leaf skeletonizer http://ipm.ucanr.edu/PMG/GARDEN/PLANTS/INVERT/plmskel.html

Bird pests in the garden-control info http://ipm.ucanr.edu/PMG/PESTNOTES/pn74152.html#IDENTIFICATION

Audubon Society-Birds of California https://ca.audubon.org/birds-0

During Napa County's shelter in place directive that protects everyone's health and safety, Napa Master Gardeners are available to answer garden questions by email: mastergardeners@countyofnapa.org. or phone at 707-253-4143.  Volunteers will get back to you after they research answers to your questions.

Visit our website: napamg.ucanr.edu to find answers to all of your horticultural questions.

Photo credits:

Grape leaf: Jack Kelly Clark UCIPM

Skeletonized leaf: Mary Kleim Attribution-NonCommercial-ShareAlike 2.0

Little bittercress: Joseph M. DiTomaso. UCIPM