California Invasive Species Week is June 3-11. This is the perfect time to raise awareness about the impact of invasive plants on our natural ecosystems and the importance of making informed plant choices. Invasive species can have detrimental effects on local flora and fauna, often outcompeting other plants for resources and disrupting local ecosystems.
By selecting plants that are well-suited to your environment and not invasive, you can make a positive contribution to preserving California's diverse landscapes. Many invasive plants can be aesthetically pleasing and low-maintenance, making them a popular choice for gardeners. However, invasive plants can spread rapidly, taking over natural habitats and causing significant environmental damage. Invasive species often have few natural predators, enabling them to grow uncontrollably and outcompete other plants for resources like water, sunlight, and nutrients. This can lead to the loss of biodiversity, reduced habitat quality for wildlife, and increased risk of erosion and wildfires.
Examples of Invasive Plants in California:
1. Periwinkle (Vinca major)-This evergreen groundcover is a popular species because of its beautiful purple blooms. Periwinkleforms dense mats that can smother native plants and alter soil chemistry. Instead of periwinkle, try planting native groundcovers like California lilac (Ceanothus spp.) or hummingbird sage (Salvia spathacea).
2. Fountain grass (Pennisetum setaceum)-This ornamental grass is highly adaptable and has invaded many natural habitats, including grasslands and coastal sage scrub. Instead, opt for native grasses like purple needlegrass (Stipa pulchra) or deergrass (Muhlenbergia rigens) or the smaller version (Muhlenbergia dubia).
3. Pampas grass (Cortaderia selloana)-A tall, clumping grass with feathery blooms that can quickly dominate landscapes and outcompete native species. Consider planting native ornamental grasses such as blue grama grass (Bouteloua gracilis) or switchgrass (Panicum virgatum) as alternatives to pampas grass.
4. Tree of heaven (Ailanthus altissima)-This fast-growing tree can release chemicals that inhibit the growth of other plants and can sprout vigorously from root fragments. Plant California native trees like sycamore (Platanus racemosa) or western redbud (Cercis occidentalis) instead of the invasive tree of heaven.
Celebrate Invasive Species Week!
organization dedicated to protecting California's wildlands from invasive plants through
research, restoration, and education.
•California Native Plant Society (CNPS)-https://www.cnps.org/-CNPS is a non-profit
organization that promotes the understanding and appreciation of California's native plants and
preserves them in their natural habitat.
•PlantRight-https://plantright.org/-PlantRight works with California's nursey industry to keep
invasive plants out of our landscapes and promotes the sale of non-invasive alternatives.
- Author: Christine Casey
An important part of the Parrella lab IPM program is evaluating new products and strategies at commercial greenhouses. This trial was an evaluation of root rot control in bedding plants that I conducted at a greenhouse on California's Central Coast. We compared biological products with a traditional fungicide. The biocontrols were RootShield (Trichoderma harzianum; BioWorks) and Activated Effective Microorganisms (AEM) (a mix of several beneficial microbes; TeraGanix); the conventional product was Pageant (pyraclostrobin and boscalid; BASF). RootShield and Pageant are labeled as fungicides, while AEM is a plant health promoter. It stimulates root growth and suppresses some pathogens; our work has shown that these two actions provide partial management of root rots.
We also tracked populations of fungus gnats, shoreflies, and moth flies as these insects can spread plant diseases in the greenhouse.
Seeds of salvia (Salvia farinacea ‘Blue Rhea'), pansy (Viola x wittrockiana ‘Morpheus') and vinca (Catharanthus roseus ‘Coconut Cooler') were sown the week of August 15; data was taken on September 1 and September 21.
Plants were evaluated two and five weeks after sowing to evaluate the percent loss per flat (visual estimate; includes both dead plants and ungerminated seed) and overall flat quality (1 to 5, with 1= all dead to 5 = all healthy). Yellow sticky cards were placed on August 31 (one card per treatment) and were counted on September 1 and September 21.
There were five replications of four treatments: AEM (1:500 dilution with weekly applications), RootShield (4 oz per 100 gallons with weekly applications), Pageant (12 oz per 100 gallons applied as per label directions), and an untreated control.
At week 2, crop loss was significantly different from the contol in the Pageant treatment (Fig. 1). We suspect this was due to phytotoxicity.
Fungus gnats, shore flies, and moth flies are an on-going concern at this greenhouse's cool, damp coastal location. During this trial fungus gnat and moth fly populations were very low (1-2 per card per week); moderate shore fly levels of 10-15 per card per week were observed.
All three treatments provided excellent crop quality with relative low plant loss. The grower's attention to sanitation and insect disease vector management explains the low disease pressure as evidenced by the lack of crop loss or poor quality in the control.