26 May 2020
Citrus Greening

Assessment of unconventional antimicrobial compounds for the control of ‘Candidatus Liberibacter asiaticus’, the causative agent of citrus greening disease.

In this study, newly identified small molecules were examined for efficacy against ‘Candidatus Liberibacter asiaticus’ in commercial groves of sweet orange (Citrus sinensis) and white grapefruit (Citrus paradisi) trees. We used benzbromarone and/or tolfenamic acid delivered by trunk injection. We evaluated safety and efficacy parameters by performing RNAseq of the citrus host responses, 16S rRNA gene sequencing to characterize citrus-associated microbial communities during treatment, and qRT-PCR as an indirect determination of ‘Ca. L. asiaticus’ viability. Analyses of the C. sinensis transcriptome indicated that each treatment consistently induced genes associated with normal metabolism and growth, without compromising tree viability or negatively affecting the indigenous citrus-associated microbiota.

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28 Apr 2020
Crop Management

Organic Orchard Management: Nutrition for Organic Orchards

In organic systems, soil fertility, crop nutrient status, and groundcover management are closely linked. As specified under the National Organic Program (NOP), “Organic producers must rely upon animal manures, compost (organic matter of animal and/or plant origin that has been decomposed by microorganisms), and cover crops to supply some, if not all, of the required nutrients for healthy crops.”

Naturally derived soil amendments have variable nutrient levels depending upon the sources from which they were derived. Therefore, nutrient availability from composts and cover crops will be specific for the soil type and crop demand in each orchard. Besides supplying nutrients, soil amendments can increase soil organic matter, balance pH levels, increase microbial activity, improve soil structure and tilth, improve drainage in clayey soils, improve water-holding capacity in sandy or gravelly soils, and help to suppress some root diseases.READ MORE

28 Apr 2020
Cover Crops

Orchard Floor Management: Cover Crops

Cover crops can be one component of orchard floor management, but are not a “system” alone. Cover crops are important in maintaining soil structure, encouraging water infiltration, reducing erosion, reducing mud and dust, and maintaining an acceptable driving surface for equipment. A good cover crop can be established with grasses, broadleaf plants such as legumes, or both, although a uniform plant stand is often easier to manage than one made up of multiple crop species. A cover crop should establish itself quickly and thereafter should not require much maintenance. It should be chosen and managed so that competition with trees is minimal.

Grasses are the most common cover crops in orchards. Many different grasses and grass mixtures are available, so orchardists can choose what is best suited to each particular situation. Several low growing perennial rye grasses are available and allow easy orchard access even when headed out.

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27 Mar 2020
Koppert Studies

Spain: Koppert studies efficacy of beneficial fungus for the biological control of HLB

Beneficial microorganisms are becoming increasingly important in the biological control of citrus pests, as a complement to the release of auxiliary insects. Proof of this is the research carried out by Koppert Spain, which aims to confirm the efficacy of an entomopathogenic fungus that could help control Trioza erytreae, one of the insects that transmits huanglongbing (HLB), or citrus greening. “Koppert’s objective is to develop a biological solution that may be available to producers if the insect that transmits the HLB arrived in Spain,” said Javier Calvo, researching entomologist at Koppert, in the framework of a Citrus Technical Conference held in El Rompido (province of Huelva) and Palma del Río (province of Cordoba).

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27 Mar 2020
Trained dogs - Citrus Greening

Trained dogs are the most efficient way to hunt citrus industry’s biggest threat

Dogs specially trained by Agriculture Research Service (ARS) scientists have proven to be the most efficient way to detect huanglongbing—also known as citrus greening—according to a paper just published in the Proceedings of the National Academy of Sciences.

Currently, the only solid hope of curtailing the spread of citrus greening is to eliminate trees with the disease as quickly as possible to prevent further spread. Early detection of the citrus greening pathogen is crucial because trees can be infected and act as a source to spread the disease months or years before showing symptoms that are detectable by the naked eye.

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27 Feb 2020
Young Citrus Grove

The Pursuit Grows to Build Organic Matter in Citrus

Florida citrus growers have always understood the importance of soil health and the positive influence of microbial activity and diversity in production. As citrus greening (also known as HLB) has spread, reducing production by more than 70%, interest in how these tiny organisms can improve root health is increasing. Research showing the disease, which is spread by the Asian citrus psyllid, can reduce citrus fibrous-root density by 30% to 50% before symptoms become visible above ground only intensifies the interest to learn more.

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27 Feb 2020
Cover Crop Management

Cover Crop Management

There are numerous management issues to consider when using cover crops. Once you decide what your major goals are for using cover crops, select one or more to try out. Consider using combinations of species. You also need to decide where cover crops best fit in your system—planted following the main crop, intercropped during part or all of the growing of the main crop, or grown for an entire growing season in order to build up the soil.

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27 Feb 2020
Soil Health

Soil Health in Orchards

Orchard soil health, or soil quality, is the capacity of soil to support productive trees over time without negatively affecting the surrounding environment. Soil health is influenced by interacting biological, physical, and chemical properties of soil. Active soil biological communities mineralize nitrogen, create soil structure, and compete with plant pathogens. Physical properties of soil determine its ability to store and release nutrients; accommodate water entry, storage, and movement; provide sufficient oxygen for roots and microbes; and moderate environmental stress. Chemical aspects of soil health include nutrient presence and availability, pH, cation exchange capacity (CEC), salinity, and the presence of any contaminants, such as heavy metals or persistent pesticide residues.

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