Posts Tagged: citrus
University of California Cooperative Extension & USDA Farm Service Agency
Emergency Avocado & Citrus Post-Wildfire Informational Meeting
We understand this is a difficult time for all of our friends, family and neighbors affected by the devastating Lilac fire. In hopes of providing some assistance and relieving some anxiety, we assembled an informational meeting to provide resources to help growers deal during this overwhelming time.
Date: Tuesday, December 19, 2017
Time: 1:00-4:00 PM
Location: 990 E. Mission Rd, Fallbrook CA 92028, Fallbrook Public Utility Building
There is no cost to attend this event
Please register at: https://ucanr.edu/survey/survey.cfm?surveynumber=22511
1:00- 1:10 - Introduction: Sonia Rios, Subtropical Horticulture Farm Advisor, UCCE Riverside/San Diego
1:10- 1:30- Fire Update and Safety: CAL FIRE
1:30- 2:00- Post Fire Tree Care- Gary Bender, Emeritus, Subtropical Horticulture Farm Advisor, UCCE San Diego
2:00- 2:20 Post Fire Tree Economics- Eta Takele, Agriculture Economics Advisor, UCCE Riverside
2:30-3:30-Desiree Garza, USDA Farm Service Agency
3:30: 3:55- Preventative Fire Safety for Orchard Systems-Sonia Rios, Subtropical Horticulture Farm Advisor UCCE Riverside/San Diego Co.
3:55 Conclude Meeting
Will also be in attendance: Eric Klein, Dept. of Environmental Health, Debra Lorenzen, Community Recovery Team, and other resource agency's will be in attendance.
Light drinks and refreshments will be served
If you have any questions, please feel free to call: Sonia Rios, 951-683-6491 ext. 224
At a recent meeting for current and prospective avocado growers near Visalia, Yosepha Shahak a retired researcher from Israel's Volcani Institute presented information on photo-selective netting. This netting was an outgrowth of netting that is used in the Mediterranean region to protect crops from frost damage and the unpredictable hail storms that can occur just as fruit might be coming to harvest. Netting is currently used in commercial orchards and vineyards throughout Europe. San Joaquin Valley growers like the idea of frost protection.
Netting over loquats (nespero) in Spain (Espana)
Netting over apples in Australia
Netting for light modification in Israel. Tractors can work here.
Photo-selective netting refers to covering crops by nets having the capacity to selectively filter the intercepted solar radiation, in addition to their protective function. The technology is based on plastic net products into which light dispersive and reflective elements are introduced during manufacturing. These nets are designed to screen various spectral bands of the solar radiation, and/or transform direct light into scattered light. The spectral manipulation intends to specifically promote desired physiological responses, which are light-regulated, while the scattering improves the penetration of the modified light into the inner plant canopy. So, depending on the crop, more and better fruit set, bigger fruit and some other desirable properties. The netting can also substantially reduce evaporative demand and wind damage. This can lead to not only lower water use, but also such water stress related diseases, such as blight caused by Botryosphaeria fungi. Lower evaporative demand and less water application can lead to less salt damage.
A recent additional aspect to the photo-selective nets refers to their effects on pest behavior. The photo-selective netting concept was developed and tested in Israel in ornamental, vegetable and fruit tree crops. It is gradually spreading all over the world, for implementation in different crops, climatic regions and cultivation methods. Applying it to avocado orchards is going to require pruning and keeping trees so that they can be picked and pollinated. And would probably lead to high density orchards.
And how we do pest management – more or less, and maybe not by helicopter?
This might also be the future for how citrus is grown in an HLB environment. 24 sprays a year to control ACP in Florida -Yikes.
A link to a Shahak talk that she gave to Washington state apple growers can be found at:
So if you have lemons, read this. And if we have rain, really read this. I think because we prune lemons so much, this is more of a lemon problem, because I've never heard of other citrus getting it. It is a wood decay fungus on a lot of other tree species, though. Does anyone know what "sambuci" translates as?
Chlorotic, undersized, sparse leaves and branch dieback are common symptoms of wood decay fungi infecting roots, the basal trunk (root crown), or limbs. These fungi include Armillaria mellea, Hyphoderma sambuci, Ganoderma spp., and Oxyporus spp. These fungi are called white rots because they often cause decayed wood to become soft and white or yellow. Brown rots, such as those caused by Antrodia sinuosa and Coniophora spp., primarily decay cellulose and hemicellulose. They leave behind the brownish wood lignin, which is usually dry and crumbly.
Wood decay fungi produce fruiting bodies on the bark, root crown, or stumps or growing from soil near trunks. Fruiting bodies may be obvious toadstool- or umbrella-shaped mushrooms like those of Armillaria spp. or large and shelflike as with Ganoderma spp. Oxyporus spp. produce bracket-shaped, seashell-shaped, or thin and pale fruit bodies. Some decay fungi, such as Antrodia and Hyphoderma spp., form relatively inconspicuous crusts on infected bark. Fruiting bodies produce numerous tiny spores that spread in wind or splashing water.
Decay fungi initiate infections when their spores contact injured tissue on living trees, such as wounds from pruning, vertebrate chewing, or infection sites of Phytophthora or other pathogens. Decay fungi can colonize stumps and infect through root grafts to adjacent trees. Spores landing on dead limbs initiate infections that spread to the attached living wood. Most decay fungi are saprophytes that can only grow on severely stressed or injured hosts, or they must first produce substantial inoculum on dead wood.
Avoid wood decay by providing trees with good growing conditions and optimal cultural care to promote vigorous tree growth. Protect bark from injury. Avoid making large wounds (such as pruning cuts), especially during the rainy or foggy season. When a tree is cut down or disease is spreading from an infected tree (such as by root contact), remove the entire tree—including the stump and major roots.
If it rains or we finally have some Valley/Tule Fog or if we have a winter with heavy dew and you have lemons, read further about Hyphoderma sambuci.
Hyphoderma gummosis is reported in the field only on lemon. It occurs in the San Joaquin Valley and coastal growing areas. This wood decay fungus causes branch wilting and dieback that ultimately results in tree death. It cannot infect its host through intact bark. To initiate infections, it requires injuries such as pruning wounds. Spores colonize exposed wood and during moist conditions produce new infections. A crust of pink to white fungal growth of Hyphoderma sambuci appears around infected wounds after wet weather.
Provide good cultural care that encourages vigorous tree growth. Prevent irrigation water from directly wetting bark. Avoid wounding bark. When pruning trees, wait at least one month after the end of the rainy season before making cuts, because Hyphoderma basidiospores require moist conditions to survive and cause infections. Prune out all infected wood during dry conditions and remove it from the orchard.
Plant Shield is a product of an antagnonistic fungus - Trichoderma harzianum- that can be painted on wounds to prevent this gummosis. It's best to just avoid pruning in wet weather, though.
photo: Crusty pink fruiting bodies and wet area on lemon branch
The whole group of plants we lump under the taxonomic classification of citrus are really changeable. It's out of this changeability that we get new varieties. Some of these can be quite fanciful, almost dream like fruit which is where the origin of the name chimera comes from. Buddha's Hand is a pretty dream-like fruit.
These changes are a genetic mutation that occurs in a branch or twig, and if that tissue survives, it can produce new shoots (called sports or chimera) with characteristics different from the those of the mother tree. These mutations can affect the color of the rind or pulp or the shape of the fruit.
Leaves on these twigs can have a different shape or size have a variegated color.
Mutations can cause the development of multiple buds, creating bunchy growth or “witches' broom.”
A chimera can produce an improved crop: some of today's cultivars were propagated from chimeras, such as the variegated pink lemon.
Usually sports are of inferior quality and should be avoided as propagation material. Prune sports that obstruct normal growth or interfere with harvest.
But some of them are so weird you just want to keep them around. This one showed up on one and only one tree branch in a lemon orchard. It looks like citrus scab, sort of, but on only one branch of one tree.
Some of the changes that you see in a tree can also be symptoms of a whole lot of other problems, like nutrients, Huanglongbing or herbicide damage. Check out some of the symptoms:http://ipm.ucanr.edu/PMG/C107/m107bpfruitdis.html
Some chimeras are yet to be found out. This image of spiral tattooing showed up for several years ago in a Meyer lemon orchard. It was erratic and inconsistent in a tree, not typical of a chimera. The orchard was finally removed because it wasn't making money. Now it just seems like a dream and will never know if it was a true chimera.