citrus packing machine

However, there appear to be no  citrus packing machine CTV-free areas among the Hawaiian Islands where quarantine procedures for new plantings might be implemented. Removing infected plants to establish CTV-free areas and replacing them with virus-free planting material would also be inef­fective, as viruliferous brown citrus aphids would soon re-infest the virus-free plantings.

Mild CTV strains that confer cross protection against severe CTV strains are well established in some citrus-production areas in Hawai‘i.  citrus packing machine Many productive trees in Hawai‘i are infected with these cross-protecting strains. Resistant or tolerant citrus varieties such as pummelo (C. maxima Merr.) and some mandarins (C. reticulata L.), popular in local markets, may be grown productively.

Quarantine, certification, and suppression/ eradication programs

Quarantine programs test incoming citrus planting stocks for CTV and other citrus pathogens that may harm a region’s citrus industry.  citrus packing machine Citrus trees are usually clonally propagated by grafting, and CTV is graft-transmissible. Thus, an important aspect of CTV management is maintaining CTV-free bud stocks. Buds from a single tree can be used to produce hundreds of new plants that may be distributed over great distances. Many CTV epi­demics were started or  citrus packing machine enhanced by the distribution of infected budwood (3). Budwood certification programs are designed to keep such budwood free of CTV and other graft-transmissible pathogens. In such programs,  citrus packing machine primary budwood source trees are regularly monitored for infections and may be further protected by insect-proof screening, or moved to locations far removed from CTV-infected trees (29). In order to reduce the number citrus packing machine of CTV-infected trees in a region, surveys are routinely conducted to detect infected trees and have them re­moved. Outside of Hawai‘i, such suppression programs are generally undertaken only if the CTV incidence is However, determining the incidence of CTV in a region is difficult where  citrus packing machine disease incidence is low, as a large number of samples must be processed to accurately estimate disease incidence. Several survey techniques have been designed to maximize the area and number of trees sampled, while minimizing  citrus packing machine the number of samples processed, often by combining samples from adjacent trees (41). If any of these combined samples are positive, a more intensive survey is conducted within the affected area to determine the extent of the infection. Although these are often called “eradication” programs, usually  citrus packing machine not all infected trees are removed, given the time lag between initial infection and when the virus is detectable by laboratory assays. If successfully implemented, how­ever, a CTV-suppression program can be cost effective and may keep CTV at acceptable levels (29).

The control methods described above can also be applied to regions where so-called mild strains of CTV are common and where the goal is to control severe strains. Strain-selective control approaches, however,  citrus packing machine require a method to discriminate between the more de­sirable strains and those severe strains to be eradicated. In Florida, which has populations of both mild and disease-inducing strains, control is focused mainly on managing the more severe, stem-pitting strains of CTV. An important component  citrus packing machine of this management strategy is the use of the antibody MCA-13, which can discriminate between mild and severe Florida strains (62) to screen trees. Trees testing positive for MCA-13 are identified for removal by the testing process. This reduces the ef­fort and expense of removing a large number of trees, and growers do not lose productive trees whose health is strengthened by the protective effects of infection by milder strains of CTV. Additionally, budwood harbor­ing CTV infections that  citrus packing machine are not reactive to MCA-13 can be propagated and distributed on a limited basis (29). A similar strain-selective control strategy was employed in California when a stem-pitting strain was introduced at a single location. Although no antibodies were available that could discriminate between the introduced strain and endemic mild strains, indicator plants were used to identify infected trees. These trees citrus packing machine were removed and the introduced strain of CTV was eradicated (29).