- Author: Elaine Lander
With the recent time change along with a change in temperatures, landscaping practices for pests need some adjusting too. We're sharing a few recommended tasks to help prevent insect pests, diseases, and environmental disorders in landscapes. Looking for additional tips? You can subscribe to our Seasonal Landscape IPM Checklist for monthly landscaping reminders delivered straight to your email inbox.
Frost Protection
Irrigation
Adjusting water schedules is an important part of integrated pest management. Different plants have different watering needs and too much or too little water can damage or kill plants. Reduce irrigation frequency or turn off automated systems if rainfall is adequate or irrigate deeply if the weather is dry. Learn more about irrigating fruit and shade trees and shrubs on our website.
Prune
Deciduous trees and shrubs such as apple, crape myrtle, pear, and peach need to be pruned to maintain their structure and health. Proper pruning can also help manage and prevent certain pests. Our website has plant-specific pruning information for a number of fruit, nut, and landscape trees. Be sure to remove dead, diseased, and borer-infested wood.
Sanitation
Now is the time to clean up old fruit and nuts under trees to avoid harboring pests. Removing fallen leaves from beneath fruit trees and roses will also help reduce insect and disease problems. This practice of sanitation is a key component of integrated pest management to prevent and reduce pests. See our website for additional sanitation tips in your landscapes and gardens.
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- Author: Lynn M. Sosnoskie
It's that time of year again. Time to get small grains seeded, especially considering that there is the potential for a weather system to move through our area next week (Wednesday, November 21, 2018).
Water in our weather? Current forecasts suggest that rain could move through the area next week.
As we move into winter, it's also time to start thinking about the potential injury that can result due to environmental conditions. Last year, farm advisors in the Central Valley received a number of calls regarding injury to small grains (wheat, oats, triticale, etc…) that were later determined to be the result of cold injury. To address this issue, Dr. Michelle Linefelder-Miles, a Farm Advisor for Delta Region, authored a really good blog post describing the situations that she experienced. Her post can be accessed at: https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=26545.
Yellowing of small grains observed in March 2018 near Turlock, CA.
Frost injury in small grains can present as tip burn, leaf chlorosis, or stem lesions; look carefully at the whorl for dead leaves or try splitting the stem to see if the growing point is water-soaked or necrotic. Remember, other types of injuries, deficiencies, diseases, and disorders can cause similar symtomology. Alternate reasons for yellowing include nitrogen deficiency, sulfur deficiency, and injury resulting from herbicide carryover from a preceding crop. To distinguish between potential scenarios, think about the following questions:
What do other small grain field in the region look like? Are the symptoms wide-spread or isolated. Are early– and late-planted field differentially affected? Was there a significant cold spell that occurred prior to the observation of injury? You can access local weather data, online, using the CIMIS network https://cimis.water.ca.gov/Stations.aspx
What parts of the plant are affected? Is the yellowing seen on older or newer tissue? For example, nitrogen deficiencies are worse on older leaves and sulfur deficiencies on younger tissue.
What is the soil texture like? Did a significant rainfall occur? Could denitrification or leaching account for the observed symptoms? Was the field fertilized properly? What were the results from your most recent soil test? Is the soil excessively wet and are the roots stunted and unhealthy looking?
Within a field, are you observing any patterns that could suggest the movement of a pest or pathogen? Are there patterns to suggest that fertilizer applications were not made uniformly? What crop preceded small grain planting and could herbicide carryover injury account for the observed symptoms? What herbicides were applied within the small grains crop? Some ALS-inhibiting herbicides registered for use in small grains can cause injury when plants are going in cool, wet soils.
So on to the important question...will this injury result in yield loss? Unfortunately, the answer is it depends. It depends on the growth stage of the plant when symptoms develop (for example, did cold injury occur when the plants were tillering (and the growing points were more protected) or when the plants were close to heading out?). It depends on whether the symptoms can be remedied (for example, is the injury the result of herbicide carryover or is it the result of a nutrient deficiency?). Please feel free to contact your local farm advisor if you see these (or other unexplained symptoms) in the coming months.
Interested in this topic? For more information about yellowing in small grains, please see the following websites:
http://blog-crop-news.extension.umn.edu/2014/05/early-seasoning-yellowing-of-wheat.html
https://cropwatch.unl.edu/soils/nutrient-deficiency-wheat
https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=26545.
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- Author: Lynn M. Sosnoskie
Part of my role as a University of California Cooperative Extension Farm Advisor is extending knowledge to my clientele and the public at large. I try to do this via this blog, through the use of social media (@agronomyweedsci on Twitter), and via popular press articles (for example, see this post about smartphone apps for weed identification: https://www.growingproduce.com/fruits/smartphone-apps-to-help-you-id-weeds/).
Another tool that I will be employing is a twice yearly (Fall and Spring) newsletter that will address issues of concern to growers in the San Joaquin Valley. Please enjoy this first installment!
Fall 2018 Agronomy and Weed Science Newsletter
In this issue:
- Research update
- Drought monitoring websites
- Cold injury, nutrient deficiencies, or herbicide carryover in small grains
- New Nutrient Management/Soil Quality Advisor
- Soil health survey
- Upcoming meetings
Fall 2018 Agronomy Weed Science Newsletter
- Author: Surendra Dara
Petals, sepals, and developing fruit damaged and darkened from freezing temperatures (Photos by Surendra Dara)
Fruit deformation as a result of low temperatures which affect pollination. Smaller achenes are formed and uneven development of the tissue around them results in misshapen fruit. Notice larger achenes in unaffected areas (Photo by Surendra Dara)
Unusual cold weather during the past few days is a concern for the strawberry growers. Second year crop and cultivars that produce early or late can influence the extent of impact experienced by the growers because injury depends on the stage of development.
Damage: Low temperatures could completely damage the flowers or injure developing fruit tissue resulting in misshapen fruit. Pollination is also affected if temperature drops below 60 oF (15 oC) during flowering. As a result, some achenes do not have a seed, remain small, and cause fruit distortion. Cold injury can also cause fruit with multiple tips. Distorted fruit from lygus bug damage have uniform sized achenes, but the achenes affected by cold injury are much smaller than those on unaffected parts of the fruit.
Protection: Sprinkler irrigation can protect the fruits from cold injury when there is no or low wind. Freezing water releases heat and protects the flowers and fruits as long as temperatures do not fall below 23 oF (-5 oC) on still nights or 25 oF (-4 oC) when wind speed is no more than 2 mph. If wind speed is more than 4 mph, sprinkler irrigation is not recommended. Sprinklers must be started before the temperatures drop to freezing levels and continued throughout that period.
The time to start irrigation for frost protection depends on the dew point. If the dew point is low, irrigation has to be started before the freezing temperature. The following table shows when irrigation should be commenced depending on the dew point.
Dew Point |
Temperature at which irrigation should start |
Dew Point |
Temperature at which irrigation should start |
32 oF (0.0 oC) |
32 oF (0.0 oC) |
23 oF (-5.0 oC) |
38 oF (3.3 oC) |
31 oF (-0.6 oC) |
33 oF (0.6 oC) |
22 oF (-5.6 oC) |
38 oF (3.3 oC) |
30 oF (-1.1 oC) |
34 oF (1.1 oC) |
21 oF (-6.1 oC) |
39 oF (3.9 oC) |
29 oF (-1.7 oC) |
34 oF (1.1 oC) |
20 oF (-6.7 oC) |
39 oF (3.9 oC) |
28 oF (-2.2 oC) |
35 oF (1.7 oC) |
19 oF (-7.2 oC) |
39 oF (3.9 oC) |
27 oF (-2.8 oC) |
35 oF (1.7 oC) |
18 oF (-7.8 oC) |
40 oF (4.4 oC) |
26 oF (-3.3 oC) |
36 oF (2.2 oC) |
17 oF (-8.3 oC) |
40 oF (4.4 oC) |
25 oF (-3.9 oC) |
37 oF (2.8 oC) |
16 oF (-8.9 oC) |
41 oF (5.0 oC) |
24 oF (-4.4 oC) |
37 oF (2.8 oC) |
15 oF (-9.4 oC) |
41 oF (5.0 oC) |
Water should be applied at 0.10-0.15 (0.25-0.4 cm) inches per hour through sprinklers to provide adequate protection. Discontinuing sprinkler irrigation during the frost period can cause more damage. If sprinkler equipment is in shortage, limit the area to be irrigated. Sprinkler irrigation to an upwind or uphill field may provide some protection to an adjacent field downwind or downhill.
Drip irrigation can also provide some protection by wetting 6-12 inch (15-30 cm) of soil before the frost period. Wet soil stores and releases more heat than the dry soil.
Reference
2008. Integrated pest management for strawberries. Second Edition. UC ANR Publication 3351.