The recent heavy rainfall and flooding events in NSW may cause some immediate damage to trees, but may also have significant long term impacts on citrus orchards, particularly those planted on heavy soils or those with impeded drainage. Previous flooding events in the MIA Previous flooding and high rainfall events occurred in the Murrumbidgee Irrigation Areas (MIA) in the 1930’s and 40’s (during the winter months) and the impacts of those events, combined with a tendency to over-water resulted in considerable decline in tree health and the death of many trees. Survey and research work undertaken by Dr. Lilian Fraser concluded that one of the main causes of tree death and decline was due to infection by the root rot fungus Phytophthora citrophthora.
Like many fruit trees species, citrus trees blossom with high profusion and thereafter exhibit massive fruitlet abscission. Current evidence indicates that this process is under hormonal and metabolic regulation (Gillaspy et al. 1993). In citrus, it has been suggested that after hormonal activation of initial fruit growth subsequent development is mostly supported by nutrient supply (Talon et al. 1997). Thus, once mineral and water requirements are satisfied, competition for photoassimilates is thought to be responsible for fruit drop (Moss et al. 1972; Powell and Krezdorn 1977; Goldschmidt and Koch 1996).
Although citrus (Citrus spp.) is sensitive to salinity, acceptable production can be achieved with moderate salinity levels, depending on the climate, scion cultivar, rootstock, and irrigation-fertilizer management. Irrigation scheduling is a key factor in managing salinity in areas with salinity problems. Increasing irrigation frequency and applying water in excess of the crop water requirement are recommended to leach the salts and minimize the salt concentration in the root zone. Overhead sprinkler irrigation should be avoided when using water containing high levels of salts because salt residues can accumulate on the foliage and cause serious injury. Much of the leaf and trunk damage associated with direct foliar uptake of salts can be reduced by using microirrigation systems.
The implementation of breeding methods requires the creation of a large and genetically diverse training population. Large-scale experiments are needed for the rapid acquisition of phenotypic data to explore the correlation between genomic and phenotypic information. Traditional sensing technologies forfield surveys and field phenotyping rely on manual sampling and are time consuming and labor intensive. Since availability of personnel trained for phenotyping is a major problem, small UAVs (unmanned aerial vehicles) equipped with various sensors can simplify the surveying procedure, decrease data collection time, and reduce cost.
The efficacy of applying biocontrol agents, chemical fungicide and nematicide as protective treatments against the soilborne parasites, Fusarium spp. (Fusaria) and citrus nematode Tylenchulus semipenetrans Cobb was evaluated. The experiment took place under field conditions in a citrus orchard cultivated with 16-year-old sweet orange (Citrus sinensis L.) osbech cv. Valencia trees grafted on sour orange (C. aurantium L.) rootstock during the growing season November 2006/ October 2007. This orchard is located at Bader district, Behera governorate, Egypt. The populations of soil fauna and flora under trees canopy were examined just before treatment, and 1, 3, 6, 9 and 12 months after the treatment application. A visual inspection for the appearance of symptoms related to Fusarium or nematode infection on treated and untreated citrus trees was carried out periodically every two weeks throughout the experimental period.
Plant growth regulators (PGRs) are a tool used to manipulate vegetative and reproductive growth, flowering, and fruit growth and development. PGRs have been successfully used in agriculture for decades to amend plant growth characteristics and maximize yield and thus grower profit. Foliar-applied PGRs are routinely used in various fruit crops for flower and fruit thinning, improving fruit set, growth and development, controlling vegetative growth, and reducing fruit drop. Citrus is no exception to the use of PGRs, which can provide significant economic advantages to citrus growers when used appropriately.
According to the Florida state legislature, PGRs are defined “as any substance or mixture of substances intended, through physiological action, for accelerating or retarding the rate of growth or maturation or for otherwise altering the behavior of ornamental or crop plants or the produce thereof, but not including substances intended as plant nutrients, trace elements, nutritional chemicals, plant inoculants, or soil amendments.”
Recent reports show that orange yield and fruit quality is on the decline in Kenya’s coastal lowlands hence need for an efficient and sustainable production system. A field study was conducted in Vitengeni, Ganda and Matuga locations within the coastal lowland of Kenya from May 2012 to April 2015 to evaluate the effect of three legume cover crops on orange fruit weight and brix. The treatments included mucuna (Mucuna pruriens), dolichos (Lablab purpureus), cowpea (Vigna unguiculata) cover crops and fallow of natural vegetation as the control.
University of California finds substance capable of controlling devastating citrus disease
Scientists at the University of California, Riverside (UCR) have found the first substance capable of controlling Citrus Greening Disease, which has devastated citrus farms in Florida and also threatens California.
The University of Florida has also been working towards a solution, as reported in March 2020.
Citrus is one of the most important fruit crops in the world, and they are particularly susceptible to postharvest damage before they reach the market for fresh consumption after storage. Green mold caused by Penicillium digitatum is considered to be the main postharvest pathogen of citrus fruit with up to 60–80% decay under suitable environment conditions.
As of July 1, the suspension of Argentinian fresh lemon exports to Europe came into force following several detections of black spot in some shipments upon arrival at European ports.
“In the last two weeks, the number of black spot detections has skyrocketed, so we believe that this has been a correct and necessary measure. As a sector, we have to find where the problem is in order to solve it. We are concerned about what has taken place this campaign, but we are even more concerned about what is to come. That is why I think Argentina should soon review the lemon export protocol for Europe. It is clear that this situation will bring changes and adjustments for future campaigns,” says Francisco Rotella, commercial director of the Argentinian lemon producer and marketer Citrusvil.