Posts Tagged: N

HLB Tolerance

By Manjul Dutt, Sheetal Ramekar and Gary England

The grapefruit was created by chance from a cross between a pummelo and a sweet orange. It was first discovered in Barbados in the 18th century.

All the commercially sold grapefruits today trace their roots back to the Duncan variety of grapefruit. Cultivars existing today were developed through natural and induced mutations as well as seedling selections. As a result, all grapefruits are very similar to one another, differing mostly in small variations in their DNA.

A recent study on a newly discovered bud sport of the Flame grapefruit, found in Bill Lennon's citrus grove in Lake County, Florida, has highlighted how natural variations can offer hope in the fight against HLB. This bud sport displayed several improved qualities. These include darker leaves, better canopy density and improved HLB tolerance compared to the Flame grapefruit from which it was derived.

Preliminary data seems to indicate that this bud sport is later maturing than regular Flame, and fruits reach maturity in early January under endemic HLB conditions (Figure 1).

Biochemical tests revealed higher chlorophyll content and lower starch accumulation, suggesting that the bud sport manages resources more efficiently under HLB stress.

Certified budwood of this new selection is freely available from the Florida Department of Agriculture and Consumer Services Division of Plant Industry's Citrus Budwood Program for nurseries and growers interested in producing it.

Manjul Dutt is an assistant professor, and Sheetal Ramekar is a postdoctoral research associate — both at the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Citrus Research and Education Center in Lake Alfred. Gary England is a UF/IFAS emeritus Extension agent.

HLB Deformed Citrus

hlb defprmed citrus

IPM for Landscapers

The University of California Statewide IPM Program presents the UC IPM Green Bulletin. This newsletter focuses on specific practices and information that landscape and structural pest management professionals can incorporate into their daily work to manage pests effectively while reducing pesticide runoff and other environmental problems.

If you have a question you would like to see answered in a future issue, send it to ucipm-community@ucanr.edu.

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ground squirrel

California HLB Quarantine Area Expanded

Agricultural officials recently expanded the areas in California quarantined for citrus greening disease [also known as huanglongbing (HLB)], which is spread by Asian citrus psyllids. The quarantined area in Orange and Riverside counties was increased by a total of approximately 31 square miles. The U.S. Department of Agriculture Animal and Plant Health Inspection Service (USDA APHIS) in cooperation with the California Department of Food and Agriculture (CDFA) took this action.

The quarantine expansions were made because of citrus greening detections in plant tissue samples collected from residential properties in Orange and Riverside counties. There are approximately 3 acres of commercial citrus in Riverside County impacted by this expansion.

USDA APHIS is applying safeguarding measures on the interstate movement of regulated articles from the quarantined areas in California. These measures parallel the intrastate quarantines that CDFA established on Oct. 22. This action is necessary to prevent the spread of citrus greening to non?infested areas of the United States.

The specific changes to the quarantined areas in California can be found on the APHIS Citrus Greening and Asian Citrus Psyllid website. USDA APHIS will publish a notice of this change in the Federal Register.

Additional information may be obtained from USDA APHIS National Policy Manager Abby R. Stilwell (abby.r.stilwell@usda.gov or 919-323?6296), or from Assistant National Policy Manager Daniel Murphy (daniel.m.murphy@usda.gov or 775-221-9237).

Learn about other HLB quarantine expansions in California earlier this year.

HLB symptoms

Fire Effects on Soil

Fires are common and we usually just think of the effects it has on plants and structures, but what impact can it have on soil. I recently came across a guide book from the US Forest Service that addresses how to evaluate fire impact on soil. Following wildfires in the United States, the U.S. Department of Agriculture and U.S. Department of the Interior mobilize Burned Area Emergency Response (BAER) teams to assess immediate post-fire watershed conditions. BAER teams must determine threats from flooding, soil erosion, and instability. Developing a postfire soil burn severity map is an important first step in the rapid assessment process. It enables BAER teams to prioritize field reviews and locate burned areas that may pose a risk to critical values within or downstream of the burned area. By helping to identify indicators of soil conditions that differentiate soil burn severity classes, this field guide will help BAER teams to consistently interpret, field validate, and map soil burn severity.

The guide is here:

https://www.fs.usda.gov/rm/pubs/rmrs_gtr243.pdf

 

field guide to soil burn

Medfly Quarantine Area Expanded

The U.S. Department of Agriculture Animal and Plant Health Inspection Service (USDA/APHIS) and the California Department of Food and Agriculture (CDFA) expanded the Mediterranean fruit fly (Medfly) quarantine in Alameda and Santa Clara counties in California twice in October.

The expansions are in response to the confirmed detections between Oct. 7 and Oct. 15 of 22 wild female Medflies, 14 of them mated, and 12 wild male Medflies from traps in trees in residential areas.

USDA APHIS and CDFA established the quarantine on Sept. 6, following the detection of a mated wild female Medfly in the city of Fremont in Alameda County on Aug. 28. That Medfly came from a trap in an orange tree in a residential area. The agencies expanded the quarantine on Sept. 11, following the detections of additional flies.

As a result of the latest detections, this quarantine area increased by 38 square miles to 121 square miles. There are 54 acres of commercial agriculture in the quarantine area.

USDA APHIS is applying safeguarding measures and restrictions on the interstate movement of regulated articles to prevent the spread of Medfly to non-infested areas of the United States, as well as to prevent the entry of these fruit flies into foreign trade. USDA APHIS is working with CDFA and the agricultural commissioners of Alameda and Santa Clara counties to respond to these detections following program guidelines for survey, treatment and regulatory actions.

The APHIS exotic fruit flies website contains a description of the new quarantine area, as well as all current federal fruit fly quarantine areas. USDA APHIS will publish a notice of these changes in the Federal Register.

Additional information on the Medfly quarantine is available from USDA APHIS National Policy Manager Richard Johnson at  richard.n.johnson@usda.gov or by phone at 301-851-2109.

Medfly-alone

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