- Author: Lauren Fordyce
The University of California Statewide IPM Program (UC IPM) has an exciting, newly updated resource to help you better understand pesticide active ingredients and the risks different active ingredients pose to people and the environment.
The Pesticide Active Ingredient Database is designed for urban audiences including the general public, Master Gardeners, nursery and garden center staff, pest control operators, landscapers, and more. The active ingredients included in this database can be found in many commonly available pesticide products in California. The database contains a variety of pesticide types, including insecticides, herbicides, rodenticides, antimicrobial products, and more.
Each active ingredient in the database has its own page where you can learn what it is, how it works, and what pests it can control. You can also view example products available to the general public or licensed professionals, and a table displaying the potential hazards of the active ingredient. The potential hazards table includes toxicity information for water quality or aquatic wildlife, natural enemies, honey bees, and people or other mammals. A glossary of pesticide terms is available as well to help you understand pesticide terminology.
You can use this database to compare toxicity ratings of pesticides by clicking the “Compare Risks” link or button found on UC IPM's Pest Notes fact sheets. This will help you find the least-toxic pesticide active ingredients to control a specific pest.
We hope you find this newly updated resource helpful and share with others who may be interested.
[Featured in the Summer 2024 edition of the Home and Garden Pest Newsletter]
- Author: Lauren Fordyce
If you've used disinfecting wipes to clean surfaces in your home, an herbicide to control weeds in your garden, or insect repellents while on a hike, then you have used a pesticide. A pesticide is any material (natural, organic, synthetic, or even homemade remedies) that is used to control, prevent, kill, or repel a pest. Pesticides are designed to be toxic against certain pests like weeds, insects, or bacteria. But when they are not used properly, pesticides can also be toxic to people and pets, and harm the environment including water quality, pollinators, and natural enemies.
February is National Pesticide Safety Education Month, a time to raise awareness about pesticide safety. Keeping yourself, your family, and the environment safe from pesticides starts with reading and understanding the pesticide label. Below are some key things to look for and follow on the label.
- Where can you use it? Some pesticides can be used on both edible and ornamental plants, indoors and outside. But other pesticides may explicitly state that they should not be used indoors, on edible plants, etc. Always be sure the label states that it can be used where you intend to use it.
- Signal words. The signal words Danger, Warning, or Caution on a pesticide label indicate the immediate (acute) toxicity of a single exposure of the pesticide to humans. Pesticides with the signal word Danger are the most toxic. Look for products with the signal word Caution, as these pose less risk of toxicity.
- What should you wear to protect yourself? When handling most pesticides, you should usually wear a long-sleeve shirt, pants, closed-toe shoes, eye protection, and chemical resistant gloves (not gardening gloves). This prevents you from being exposed to the pesticide through your skin, eyes, lungs, or mouth. For some other pesticides, like insect repellents you apply to your skin, read and follow the label for specific instructions.
- How long after applying can you enter the treated area? For many home-use pesticides, you can enter the treated area when the pesticide has dried. Entering an area where the pesticide is still wet can expose you to those chemicals. Some pesticide products may state that you must wait a certain number of hours before reentering the area.
- When can you harvest treated produce? If you applied a pesticide to your edible plants it's important to know when it is safe to harvest and consume them. Many pesticides can be applied to edible crops up until the day of harvest, but some pesticides may require days or weeks to pass before it is safe to do so.
- How should you store the pesticide? Pesticides should always be stored in their original container with the lid tightly sealed, in a locked storage cabinet where children cannot access them. Improper pesticide storage can lead to exposure incidents, such as a child drinking a pesticide or spilling it on yourself.
Following the pesticide label can prevent unintentional pesticide exposure to people and pets. To prevent harm to the environment, you should also follow these general guidelines:
- Don't apply pesticides in rainy or windy weather. If it is actively raining and windy, or rain is expected, hold off on applying the pesticide. Applying during rainy or windy weather can cause the pesticide to be washed away, polluting stormwater and waterways. It can also cause drift, which is when pesticide droplets or dust move through the air. Drift can harm nearby plants, bodies of water, or people.
- Don't spray plants in bloom. Protect pollinators and natural enemies (good bugs) that feed on pollen and nectar by not spraying flowering plants.
- Dispose of pesticides at your local household hazardous waste (HHW) site. Pesticide containers that are partially or entirely filled should be taken to a HHW site to prevent environmental contamination. Empty, rinsed pesticide containers can be disposed of in the garbage or recycled if accepted in your area.
Happy National Pesticide Safety Education Month. Visit Pest Notes: Pesticides: Safe and Effective Use in the Home and Landscape to learn more about pesticide use and safety.
- Author: Kathy Keatley Garvey
And well you should: honey bees are the global workhorses of the pollination community and pollinate about one-third of the food we eat, including fruits and vegetables and some nuts, primarily almonds (California's almond acreage exceeds 1.6 million.)
But to continue the alliteration--butterflies, bats, birds and beetles are pollinators, too.
That includes "the good guys and gals," the lady beetles, aka ladybugs, which devour aphids.
However, this is National Pollinator Week and a good time to reiterate that insects can be both pollinators and pests. Take the blister beetles (family Meloidae, which contains about 2500 species) are one color or striped. Blister beetles are a pest of alfalfa and many species secrete a poisonous chemical called cantharidin, which protects them from their predators but is quite toxic to livestock, especially horses.
According to the Alfalfa Pest Management Guidelines published by the UC Statewide Integrated Pest Management Program (UC IPM): “Blister beetles do not cause widespread feeding damage to alfalfa; however, they contain a chemical, cantharidin, which is toxic to livestock. Cantharidin is contained in the hemolymph (blood) of the beetles, and can contaminate forage directly, when beetles killed during harvest are incorporated into baled hay, or indirectly, by transfer of the hemolymph from crushed beetles onto forage. Horses are particularly susceptible to the toxic effects of cantharidin. Consuming as few as six beetles can kill a horse.”
A 2020 news story out of the Midwest related that beetle-infested hay purchased at an auction in South Dakota led to the deaths of 16 horses at a riding stable in Mauston, Wisconsin. Reporter Carleen Wild wrote that even a small amount of the bug itself or cantharidin "can be toxic enough to kill a horse within 72 hours." The horse owners reported what looked like "blisters and holes down their esophagus and throughout their insides."
The odorless, colorless chemical also blisters the human skin; physicians use it to remove warts.
That's one powerful chemical.
- Author: Devii R. Rao
- Posted by: Gale Perez
Saharan mustard has been documented in eastern San Benito County on Panoche Road; in western Fresno County; in Monterey County at Fort Hunter Liggett; and in San Luis Obispo County it is concentrated near Morrow Bay and north of Santa Maria, but has been identified elsewhere as well. Below is an image from the CalFlora website showing documented locations of Saharan Mustard. For the interactive version of the map, click here to go to CalFlora then you can click on individual observations to get more detailed information.
The plants bloom from January to June (Ihsan 2012). It is not known how long the seeds can live in the soil, but scientists think they can survive for many years.
If you see this plant please let me know. You can email me at drorao@ucanr.edu or call me at 831-637-5346 x14. If you have a plant that looks like Saharan mustard, but you're not sure if that's what it is, you can bring (or mail) the plant to my office and I can identify it for you. My office is located at 3228 Southside Road, Hollister, CA 95023, right next to the Ag Commissioner's office.
For more information about Saharan mustard and how to control it click here for the UC Weed Report.
All information for this article comes from DiTomaso, J.M., G.B.Kyser et al. (2013), unless otherwise noted.
References
CalFlora. 2018. Calflora: Information on California plants for education, research and conservation,
with data contributed by public and private institutions and individuals, including the Consortium of California Herbaria. [web application]. 2018. Berkeley, California: The Calflora Database [a non-profit organization]. Available: http://www.calflora.org/ (Accessed: Feb. 12, 2018).
DiTomaso, J.M., G.B. Kyser et al. 2013.Weed Control in Natural Areas in the Western United
States. Weed Research and Information Center, University of California. 544 pp. http://wric.ucdavis.edu/information/natural%20areas/wr_B/Brassica_tournefortii.pdf accessed February 12, 2018.
Ihsan A. Al-Shehbaz. 2012. Brassica tournefortii, in Jepson Flora Project (eds.) Jepson eFlora, http://ucjeps.berkeley.edu/eflora/eflora_display.php?tid=16085, accessed on February 12, 2018.
- Author: Craig Kallsen
University of California (UC) researchers and private industry consultants have invested much effort in correlating optimal citrus tree growth, fruit quality and yield to concentrations of necessary plant nutrients in citrus (especially orange) leaf tissue. The grower can remove much of the guesswork of fertilization by adhering to UC recommendations of critical levels of nutrients in the tissues of appropriately sampled leaves. Optimal values for elements important in plant nutrition are presented on a dry-weight basis in Table 1. Adding them in appropriate rates by broadcasting to the soil, fertigating through the irrigation system or spraying them foliarly may correct concentrations of nutrients in the deficient or low range. Compared to the cost of fertilizers, and the loss of fruit yield and quality that can occur as a result of nutrient deficiencies or excesses, leaf tissue analysis is a bargain. At a minimum, the grower should monitor the nitrogen status of the grove through tissue sampling on an annual basis.
Leaves of the spring flush are sampled during the time period from about August 15 through October 15. Pick healthy, undamaged leaves that are 4-6 months old on non-fruiting branches. Select leaves that reflect the average size leaf for the spring flush and do not pick the terminal leaf of a branch. Typically 75 to 100 leaves from a uniform 20- acre block of citrus are sufficient for testing. Generally, the sampler will walk diagonally across the area to be sampled, and randomly pick leaves, one per tree. Leaves should be taken so that the final sample includes roughly the same number of leaves from each of the four quadrants of the tree canopy. Values in Table 1 will not reflect the nutritional status of the orchard if these sampling guidelines are not followed. Typically, citrus is able to store considerable quantities of nutrients in the tree. Sampling leaves from trees more frequently than once a year in the fall is usually unnecessary. A single annual sample in the fall provides ample time for detecting and correcting developing deficiencies.
Table 1. Mineral nutrition standards for leaves from mature orange trees based on dry-weight concentration of elements in 4 to 7 month old spring flush leaves from non-fruiting branch terminals.
element |
unit |
deficiency |
low |
optimum |
high |
excess |
|
|
|
|
|
|
|
N |
% |
2.2 |
2.2-2.4 |
2.5-2.7 |
2.7-2.8 |
3.0 |
P |
% |
0.9 |
0.9-0.11 |
0.12-0.16 |
0.17-0.29 |
0.3 |
K (Calif.*) |
% |
0.40 |
0.40-0.69 |
0.70-1.09 |
1.1-2.0 |
2.3 |
K (Florida*) |
% |
0.7 |
0.7-1.1 |
1.2-1.7 |
1.8-2.3 |
2.4 |
Ca |
% |
1.5 |
1.6-2.9 |
3.0-5.5 |
5.6-6.9 |
7.0 |
Mg |
% |
0.16 |
0.16-0.25 |
0.26-0.6 |
0.7-1.1 |
1.2 |
S |
% |
0.14 |
0.14-0.19 |
0.2-0.3 |
0.4-0.5 |
0.6 |
Cl |
% |
? |
? |
<0.03 |
0.4-0.6 |
0.7 |
Na |
% |
? |
? |
<0.16 |
0.17-0.24 |
0.25 |
B |
ppm |
21 |
21-30 |
31-100 |
101.260 |
260 |
Fe |
ppm |
36 |
36-59 |
60-120 |
130-200 |
250? |
Mn |
ppm |
16 |
16-24 |
25-200 |
300-500? |
1000 |
Zn |
ppm |
16 |
16-24 |
25-100 |
110-200 |
300 |
Cu |
ppm |
3.6 |
3.6-4.9 |
5 - 16 |
17-22? |
22 |
*California and Florida recommendations for K are sufficiently different that they are presented separately. The California standards are based on production of table navels and Valencias, and those for Florida were developed primarily for juice oranges like Valencia.
The sampled leaves should be placed in a paper bag, and protected from excessive heat (like in a hot trunk or cab) during the day. If possible, find a laboratory that will wash the leaves as part of their procedure instead of requiring the sampler to do this. Leaf samples can be held in the refrigerator (not the freezer) overnight. Leaves should be taken to the lab for washing and analysis as quickly as is feasible.
Often separate samples are taken within a block if areas exist that appear to have special nutrient problems. The temptation encountered in sampling areas with weak trees is to take the worst looking, most severely chlorotic or necrotic leaves on the tree. Selecting this type of leaf may be counter-productive in that the tree may have already reabsorbed most of the nutrients from these leaves before they were sampled. A leaf-tissue analysis based on leaves like this often results in a report of general starvation, and the true cause of the tree decline if the result of a single nutritional deficiency may not be obvious. Often in weak areas, it is beneficial to sample normal appearing or slightly affected leaves. If the problem is a deficiency, the nutrient will, generally, be deficient in the healthy-looking tissue as well.
Groves of early navels that are not normally treated with copper and lime as a fungicide should include an analysis for copper. Copper deficiency is a real possibility on trees growing in sandy, organic, or calcareous soils. For later harvested varieties, leaves should be sampled before fall fungicidal or nutritional sprays are applied because nutrients adhering to the exterior of leaves will give an inaccurate picture of the actual nutritional status of the tree.
Usually leaf samples taken from trees deficient in nitrogen will overestimate the true quantity of nitrogen storage in the trees. Trees deficient in nitrogen typically rob nitrogen from older leaves to use in the production of new leaves. Frequently, by the time fall leaf samples are collected in nitrogen deficient groves, these spent spring flush leaves have already fallen. Nitrogen deficient trees typically have thin-looking canopies as a result of this physiological response. Since the spring flush leaves are no longer present on the tree in the fall when leaves are sampled, younger leaves are often taken by mistake for analysis. These leaves are higher in nitrogen than the now missing spring flush leaves would have been and provide an inaccurately higher nitrogen status in the grove than actually exists.
Critical levels for leaf-nitrogen for some varieties of citrus, like the grapefruits, pummelos, pummelo x grapefruit hybrids and the mandarins, have not been investigated as well as those for oranges. However, the mineral nutrient requirements of most citrus varieties are probably similar to those for sweet oranges presented in Table 1, except for lemons, where the recommended nitrogen dry-weight percentage is in the range of 2.2- 2.4%.
A complete soil sample in conjunction with the leaf sample can provide valuable information on the native fertility of the soil with respect to some mineral nutrients and information on how best to amend the soil if necessary to improve uptake of fertilizers and improve water infiltration.
P.S. from Ben Faber
What has been said here about citrus is also generally true for avocado, although the nitrogen sufficiency levels are lower than for citrus. For a more detailed discussion see: http://www.californiaavocadogrowers.com/sites/default/files/documents/11-Final-Report-Issued-Giving-Tools-for-Fertilization-and-Salinity-Management-Winter-2016.pdf
Photo: Nitrogen deficient avocado leaf