Administration, Financial & Sales Division - Citrus Research & Education Institute
Buying Plants
A characteristic of HLB, is that is very difficult, if not impossible, to detect the presence of the disease in very young plants. This is because a young plant could be infected with a very small amount of the bacteria, so small that it is not possible to detect through a lab test. Over time, however, the bacteria multiplies in the plant to a level where the typical leaf symptoms are expressed and where it is then possible to make a detection using a lab test. This process could take a few months to a few years from the time that the plant was initially infected, by the Asian Citrus Psyllid (ACP), with the disease. The current consensus, from those who are experienced with HLB, is that young plants infected with the disease are unlikely to survive long enough to produce fruit.

Once HLB-greening disease is in a territory there is only one recognized method of producing a plant not infected with the disease. That is, to produce it in a nursery that is screened so as to prevent the disease's vector, the Asian Citrus Psyllid (ACP), from feeding on the plants.

Considering this information, therefore, growers need to make sure that the plants they buy are free of HLB and that ACP can be kept totally way from them for at least the first 4 years of their life.

Growers should consider the following issues when buying plants:

    (i)That plants are free of HLB - that is, that they have been purchased from a BAHA Certified screened nursery - certified under the BCCP regulations
    (ii)That the plants have been treated in the nursery with a systemic insecticide prior to delivery
    (iii)That the growers have good ACP control in the field - which will include being prepared (according to their budget and time) to make regular systemic insecticide applications in the field until the trees are 3-4 years old
    (iv)That the growers are prepared to regularly scout for HLB-greening symptoms in the young trees, get them tested in the CREI HLB-lab and proactively remove HLB-positive trees
    (v)That the incidence of HLB in mature trees, in the vicinity of the young trees being planted, should be very low or zero. The need for this consideration is because young trees will tend to flush vigorously and so attract large populations of ACP. If neighbouring mature trees are infected with HLB the younger trees will very likely and very quickly also become infected with HLB
    (vi)Because of issues raised in (v) growers should consider not re-planting with re-sets but replanting the entire grove (all trees at the same time) once all grove trees have been destroyed because of HLB infections
    (vii)That the life of a productive grove might now be only 15 to 20 years old
    (viii)Planting at a much higher density than the current standard of 116 plants per acre - densities of over 200 plants or 300 plants per acre are being considered in some countries

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