Category: Uncategorized

1. Invest in prevention

Prevention is better than a cure. This is particularly true of fall armyworm, as once it has found itself in a new territory, the only thing countries can do is to control its presence and manage the damage. Countries should set up prevention and preparedness plans while the pest is still absent. Check the guidelines to find the important elements to include in this plan. Investing in prevention saves countries technical and financial resources.

2. Evaluate the risk

Fall armyworm causes annual yield losses worth USD 9.4 billion in Africa alone. Based on estimates from 12 African countries, up to 17.7 million tonnes of maize, enough to feed tens of millions of people, could be lost annually on the continent if this pest is not properly prevented and managed. Fall armyworm feeds on more than 80 crops, including maize, wheat, sorghum, millet, sugarcane and cotton with potentially devastating consequences on food security and livelihoods. To prevent this, countries can conduct a pest risk analysis to determine the pathways by which fall armyworm may enter and strengthen the phytosanitary measures to be taken against it.

FAO and the International Plant Protection Convention have developed prevention, preparedness and response guidelines to help countries minimize the spread of the pest and protect their territories. ©FAO/Lekha Edirisinghe

3. Coordinate and cooperate

Every year, over 180 countries from all over the world come together to adopt international standards for plant health and identify measures to ensure that plants and crops entering a country aren’t carrying pests that are subject to quarantine. Once a country knows it is at particular risk of fall armyworm entering, it should update the status of the pest and the list of commodities subject to any phytosanitary import requirements. This action is crucial to trade plants and agri-food products in a safe manner and to avoid pests being introduced with commodities, vehicles or other means.

Currently, countries in southern Europe, the Near East and North Africa and the Pacific regions are particularly at risk of introduction.

4. Stop fall armyworm at borders

Border officials must be well trained to stop fall armyworm by all possible pathways. Luckily, fall armyworm can be spotted and identified without any special equipment. A hand lens and a close eye are enough to detect this pest, even in its early stages. Border inspectors should check the underside of leaves for eggs and use pheromones traps during inspection. Adult worms can be found in commodities that are transported and chilled; laboratory diagnostics can also confirm specimens found.

As one successful example, through phytosanitary inspections of consignments at entry points, the European Food Safety Authority (EFSA) was able to intercept the fall armyworm on commodities entering Europe. These included sweet or hot peppers, eggplants, asparagus, maize, cut rose flowers and other plant species that are not major fall armyworm hosts. According to EFSA estimates, over a million individual larvae could enter the European Union annually through host commodities.

Border officials must be well trained and prepared to spot and stop fall armyworm. Luckily, it can be seen and identified without any special equipment. ©FAO/Lekha Edirisinghe

5. Let others know about the risk

Communication is critical not only to monitor and manage fall armyworm before and after incursion but also to share information and best practices that may help countries take appropriate actions against the pest. Developing pest risk communication strategies and stakeholder awareness programmes is essential to help farmers, growers and the industry in general get ready in case of a fall armyworm introduction. Government agencies and plant protection organizations can provide technical advice on how to identify fall armyworm and the way to report its presence to national authorities.

For example, the plant protection service of Lombardia, Italy has launched a mobile application to engage citizens and professionals together in pest prevention and rapid alert. Through the FitoDetective app, people can learn more about pests, including fall armyworm, and send reports, which will be verified by local phytosanitary inspectors.

Preventing the spread of fall armyworm and other harmful pests to new areas is a global task. By implementing the FAO/IPPC guidelines on fall armyworm prevention, preparedness and response, countries can make a collective effort to minimize food and livelihood losses and protect plant health around the world.

—NPV series, Mamestra brassicae NPV and Helicoverpa armigera NPV

—Paecilomyces lilacinus to kill nematodes

—Tea Saponin using as Molluscicide

—Metarhizium anisopliae, Beauveria bassiana and Celangulin as insecticides

—Trichoderma harzianum and Bacillus subtilis as fungicides

—γ-PGA & Chitosan/Chitosan Oligosaccharide for promoting rooting, germination and growth.

Life form: Bacterium

Origin: Asia and Africa 

Distribution: Varies, depending on the species

Features: Yellowing, blotchy mottling and unseasonal leaf  flushing, leaf drop, dieback of branches .

Pathways: Imported plant propagative material, infected insects

At risk: Commercial citrus varieties & relatives

Huanglongbing (yellow dragon disease), previously known as citrus greening disease, is one of the worst diseases of citrus trees worldwide. It is caused by the bacterial disease Candidatus Liberibacter asiaticus that spreads through the tree canopy, causing decline and then death of the tree.

There is no cure – the only way to stop the disease is to destroy all infected trees and replace them.

The disease huanglongbing originated from China, with its vectors from Asia (Asiatic citrus psyllid) and Africa (African citrus psyllid). Depending on the species, the disease and its vectors can now be found throughout:

• North, Central and South America
• South East Asia, including Indonesia and East Timor
• Papua New Guinea.

The islands of Torres Strait provide a potential pathway for the movement of serious pests into Australia, such as huanglongbing and the Asian citrus psyllid, present in countries to our north.

How to identify Huanglongbing (Candidatus Liberibacter asiaticus)

Everyone needs to keep an eye out for symptoms of huanglongbing.

Huanglongbing is spread by the movement of infected plants and plant propagative material and by sap sucking insects. These insects – the Asiatic citrus psyllid (Diaphorina citri) and African citrus psyllid (Trioza erytreae) – are not present in Australia and are of major concern due to their ability to spread huanglongbing.

• Adults of the Asiatic citrus psyllid are 3-4 millimeters long with brown markings on the wings. When feeding on the veins of the young leaves, they adopt a ‘head-down, tail-up’ position.
• Juvenile psyllids are yellow and commonly found feeding on young, soft shoots.

The African citrus psyllid is similar but larger with a light brown-grey body and black head, and large transparent forewings.

Psyllids

Huanglongbing causes yellowing of citrus plant leaves and in some instances deformed, sour and bitter fruit.

• Symptoms on leaves are subtle and hard to pick but one key sign is a blotchy yellowing that is not symmetrical or mirrored on both sides of the leaf.
• Later, new young leaves are small, upright and yellow, with green bands around the veins.

In well-managed orchards, a yellowing that spreads slowly over the tree and through an orchard is an easily seen sign. The spreading yellowing effect can be especially hard to see in neglected backyard citrus trees growing in poor soils.

Infected trees have a blotchy yellowing that is not symmetrical or mirrored on both sides of the leaf Source: DAWR

Fruit from infected trees can be misshapen or lopsided, and when cut lengthwise, the arrangement of internal tissues may be irregular Source: DAWR

Methylation Vegetable oil can improve the spreading area, adhesion and permeability of droplets on the surface of the crop, and promote the absorption and conduction in crop.

Besides, the methylated vegetable oil can prevent the liquid droplets from drying too fast, thereby enhancing the absorption of droplets through pores and the stratum corneum, and enhances efficacy for herbicides.

Chemical name : N,N’-Dimethylolurea
Formula : C3H8N2O3
Molecular Weight : 120.1
CAS No. : 140-95-4

Dimethylolurea is used to treat textiles and wood, and is mixed with fillers for use in molding adhesives. And used in disinfectants and other biocidal products, as an in-can preservative, as a preservative for liquid-cooling and processing systems, and as a slimicide. Dimethylolurea is also used as a preservative in metal-working fluids, as a developer of photographic film, and as a cleaning agent and disinfectant.

Tomato plants (Lycopersicum esculentum Mill) grown under tropical field conditions were treated with an alkaline seaweed extract made from Ascophyllum nodosum (ASWE).

Two field experiments and one greenhouse experiment were conducted to evaluate methods of application, dosage of application, and the impact of each on plant growth parameters and on the quality and yield of fruit.

Field experiment 1 included 0.2 % ASWE spray, 0.2 % ASWE root drench, fungicide spray and combinations of the above. Plants foliar-sprayed with 0.2 % ASWE had significantly increased plant height (10 %) and plant fruit yield (51 %) when compared to control plants. Similar results were observed for ASWE spray alternated with fungicide or with ASWE root drench. Field experiment 2 included 0.5 % ASWE spray, fungicide spray and ASWE spray alternated with fungicide. The higher concentration of ASWE resulted in a significant increase in plant height (37 %) and plant fruit yield (63 %) compared to control plants. The third experiment under greenhouse conditions also showed that 0.5 % ASWE spray caused a significant increase in plant height (20 %) and plant fruit yield (54 %) compared to control plants.

In the greenhouse, ASWE-treated plants had larger root systems and increased concentrations of minerals in the shoots. Fruit from plants treated with ASWE showed significant increases in quality attributes including, size, colour, firmness, total soluble solids, ascorbic acid levels and mineral levels.

Overall, the use of ASWE resulted in clear improvements in tomato fruit yield and quality under tropical growing conditions.

 

Content from https://link.springer.com/article/10.1007/s10811-015-0608-3

The fact that the biosynthesis of active GAs (see Glossary) is a complex, multistepped process with diverse intermediates (Figure 1) makes it difficult to pinpoint the exact tissue or organ in which GAs are synthesized and localize to. Studies focusing on the spatial organization of the GA biosynthesis pathway, characterizing the expression patterns of different GA biosynthetic enzymes using GUS as a reporter, have led to several insights. First, GA biosynthesis genes are differentially expressed among different tissues, cell types, and developmental stages . Second, several members of the GA3ox family, which catalyze the final step in the synthesis of bioactive GAs, are expressed in growing and elongating shoot and root organs . Third, although there are several examples of tissues in which the expression of GA biosynthesis genes co-localizes with GA perception genes (e.g., in inflorescence meristem and developing leaves), there are also examples where these two groups do not overlap (e.g., GA-biosynthesis genes are not expressed in the aleurone cells of the endosperm but GA signaling genes are) . Such spatial separation between genes involved in GA biosynthesis and perception suggests the requirement for GA movement. Finally, levels of expression of genes constituting the GA biosynthetic pathway itself do not always coincide . For example, the expression of the late stage GA biosynthesis genes AtGA3ox1 and AtGA3ox2 in germinating embryos is spatially different from that of the early GA biosynthesis gene AtCPS. This and other examples suggest that the location of GA precursors could play an important role in regulating GA responses.

Figure 1. Gibberellins are Mobile Signaling Molecules in Plants. Illustration of a schematic plant (left) and gibberellin (GA) biosynthesis pathway (right). Arrows indicate documented long-distance movement of mobile GAs. The arrows are color-coded to correlate with GA forms shown in the biosynthetic pathway. Root-to-shoot and shoot-to-root movement of GA₁₂ in Arabidopsis and GA₂₀ in Pisum sativum (blue) . GA₉ movement from the ovaries to the sepals and petals was shown in Cucumis sativus flowers (red) . Movement of GA from leaves to stem was demonstrated in tobacco and Arabidopsis and from stamens to petals in Arabidopsis and Petunia (black); in these cases, the exact form of mobile GA is not clear.

A recent study, combining mathematical and experimental approaches, compared the putative GA response, represented by the expression pattern of the SCR3 GA responsive gene (pSCR3:GUS reporter) and GA perception sites, represented by the expression pattern of GA perception proteins (GID1 and DELLA). The study demonstrated that alternating temperatures act as an instructive signal in the embryonic root tip in Arabidopsis dormant seeds . The modeling nicely showed that the process of dormancy break in the seed is defined by the distribution of the plant hormones GA and abscisic acid (ABA) . This spatial separation of ABA and GA responses suggests that crosstalk between ABA and GA is non-cell-autonomous and is controlled at the level of hormone movement between spatially separated signaling centers .

It should be noted that the observations and interpretations regarding GA localization are limited by several factors. First, the spatiotemporal resolution of the studies, using GUS reporters or mRNA expression, is relatively low. It would be constructive to increase the resolution of such studies through dynamic monitoring of fluorescent reporters. Second, only a few of the GA biosynthesis genes families, and only a few members from those families, have been analyzed so far. In order to draw a comprehensive map of the spatial distribution of GA biosynthesis, a concurrent characterization of the whole pathway will be required. Third, studies to date have usually analyzed expression of GA biosynthetic genes at the mRNA level. As it is possible that these enzymes are subjected to post-translational modifications and non-cell-autonomous movement, it will be important to examine their localization as translational fusions. The ultimate goal should be to generate specific sensors that will provide a readout for the enzyme family activity. This would allow a specific readout of the final enzymatic biochemical activity and overcome redundancies. It is reasonable to assume that GA localization is also regulated by catabolism, conjugation, and transport steps . Thus, expression patterns of GA biosynthesis genes will not necessarily enable identification of all sites of active GA localization and response.

In order to overcome several of the limitations illustrated above, a novel fluorescence resonance energy transfer-based GA biosensor (termed GPS1) was developed. The GPS1 biosensor, constructed by fusing GID1 variants to the DELLA N-termini, showed an increased emission ratio in response to nanomolar concentrations of GA₄. With the exception of a few limitations such as nonreversible response to GA₄, phenotypic hypersensitivity to a GA biosynthesis inhibitor, and a limited response to GA₃ and GA₁, this biosensor should be a useful new tool for identifying GA response sites. For example, GPS1 revealed that GA response is higher in the elongation zone compared with the root meristematic zone. GA localization correlated with cell length when GA₄ was exogenously applied, suggesting that rapid transport or catabolism of GA in the root may generate local GA gradients independently of GA biosynthesis. In addition, the GPS1 sensor indicated that high levels of GA₄ in the elongating hypocotyl depend on darkness . GPS1 should find broad utility in exploration of GA distribution and transport mechanisms and is expected, for example, to shed light on GA distribution in known and novel GA transporter loss-of-function and gain-of-function lines reported for the nitrate transporter 1/peptide transporter family (NPF) and SWEET families  (further discussed below).

A different approach to address the question of GA distribution and accumulation sites utilized fluorescently labeled versions of GA₃ and GA₄ (termed GA-Fl). Combining imaging of GA-Fl localization with information on transporter expression levels and genetics showed that the TEMPRANILLO (TEM) proteins play an essential role not only in GA biosynthesis but also in regulating GA distribution in the mesophyll, which, in turn, regulates epidermal trichome formation . In roots, GA-Fl accumulated specifically in the elongating endodermal cells of Arabidopsis roots. The localization of GA-Fl in the elongating cells is consistent with GFP-RGA levels and with other studies indicating that GA activity is necessary for root elongation and gravitropic response , but only partially overlaps with GPS1 signal, which was not restricted to the endodermis. Since GA-Fl is highly specific to NPF3 , it is possible that it represents only a subset of GA forms. Alternatively, it is possible that GPS1 and GA-Fl report on GA levels on different sites within the cell; whereas GPS1 mainly responds to nuclear GA₄ levels, the fluorescent GA₄ reports on transport and localization of exogenously applied GA that eventually localizes to the vacuole. Since the GA response was shown to be restricted to the root endodermis cell layer,  it will be important to evaluate the distribution of active GA and its precursors at a cellular resolution, as has been successfully carried out for the plant hormones auxin and cytokinin .

Cells entering the elongation zone increase in length by approximately 10-fold over 5 hours. Such a rapid expansion is expected to result in a rapid intracellular dilution of GA, practically reducing its effective concentration. Modeling of this process suggests a correlation between GA distribution and root cell growth, and the study authors posit that cellular GA levels decrease at the elongation zone due to cytosolic dilution . Independent analyses of the GPS1 sensor response and GA-Fl distribution indicate that GA levels are higher in the root elongation zone compared with the meristematic zone; therefore, GA is probably either synthesized locally or imported from surrounding tissues to compensate for dilution.

Gibberellin (GA) was first identified in the pathogenic fungus Gibberella fujikuroi, which causes a disease in rice called ‘foolish-seedling’.

By producing large quantities of GA, the plants become long and slender, are incapable of supporting their own weight, and are chlorotic and partially infertile .

Further research established GA as a hormone that is essential for many developmental processes in plants, among them are seed germination; organ elongation and expansion through cell growth; trichome development; transition from vegetative to reproductive growth; and flower, seed, and fruit development .

GA manipulation in agriculture is common practice; the best-known contribution of GA manipulations to agriculture is the introduction of dwarfing alleles into staple crops. This manipulation resulted in one of the cornerstones of the so-called ‘green revolution’ and led to a massive increase in global wheat and rice yields. Identification of the genes responsible for these traits showed that the encoded proteins interfere with the action or production of GA .

Among more than 130 GAs identified in plants, fungi, and bacteria to date, only a subset, namely GA₁, GA₃, GA₄, and GA₇ are thought to function as bioactive hormones .

Additional forms of GA that exist in plants are precursors of the bioactive forms or deactivated metabolites .