CorseMachin
Decline (slow or quick) occurs when scions are budded onto sour orange rootstocks and become infected with certain strains. CTV causes death of the phloem below the graft union so that carbohydrates from the leaves cannot reach the roots, and nutrients and water from the roots cannot reach the leaves.
- Which technique is used to prevent the tristeza virus in citrus?
- How is the citrus tristeza virus spread?
- Where is citrus tristeza virus found primarily?
- Which rootstock is tolerant to tristeza virus?
- What is cross protection technique in citrus?
- What causes citrus canker?
- What are the symptoms of citrus greening?
- What is citrus decline?
- What is stem pitting?
- What type of microbe is behind citrus greening disease?
Which technique is used to prevent the tristeza virus in citrus?
Control of tristeza in citrus orchards is obtained by indirect methods. In new plantings made in invaded areas, non-tolerant stock-scion combinations should be avoided. Only tolerant rootstocks such as sweet oranges, mandarins, rangpur lime, and rough lemons should be used for most commercial tops.
How is the citrus tristeza virus spread?
Citrus tristeza virus (CTV) is transmitted by several aphid species in a semi-persistent manner with Toxoptera citricida, the brown citrus aphid (BrCA), being the most efficient. As yet, the molecular interactions between the virus and its aphid vectors have not been determined.
Where is citrus tristeza virus found primarily?
There are currently two strains of the virus found in Arizona, primarily from Meyer lemon trees. One is severe, the other is mild. Many Arizona citrus trees have scions and rootstocks that are quite susceptible to the severe strain of CTV.
Which rootstock is tolerant to tristeza virus?
Since the virus has been in Asia a long time they have used rootstock from trifoliate orange, Sunki, and Shiikuwasha (C. × depressa) for many years. Some hybrids, such as Troyer citrange or Swingle citromelo, show promise as resistant root-stock. Also, using scion varieties tolerant to stem pitting is recommended.
What is cross protection technique in citrus?
Cross-protection, a phenomenon in which a pre-existing viral infection prevents a secondary infection with the same or closely related virus, was first demonstrated by McKinney (1926, 1929) between two genotypes of Tobacco mosaic virus.
What causes citrus canker?
Citrus canker, caused by the bacterium Xanthomonas citri subsp. citri, affects the leaves, twigs and fruit of citrus plants causing the leaves to drop and unripe fruit to fall to the ground. All types of citrus are affected by the disease.
What are the symptoms of citrus greening?
Signs and Symptoms
- Visible psyllids or waxy psyllid droppings.
- Lopsided, bitter, hard fruit with small, dark aborted seeds.
- Fruit that remains green even when ripe.
- Asymmetrical blotchy mottling of leaves.
- Yellow shoots.
- Twig dieback.
- Stunted, sparsely foliated trees that may bloom off season.
What is citrus decline?
Citrus decline, commonly known as 'dieback' is also known as 'chlorosis' or neglectosis is not a specific disease but a syndrome expressing many disorders in the plant leads to decline in productivity, reduced productive life and poor fruit quality.
What is stem pitting?
Mandarin stem-pitting is caused by a strain of Citrus tristeza virus (CTV), which belongs to the Closterovirus genus. There are many different strains of CTV, each producing a different suite of symptoms on different citrus cultivars and rootstocks. The mandarin stem-pitting strain is particularly severe on mandarins.
What type of microbe is behind citrus greening disease?
The causative agents are motile bacteria, Candidatus Liberibacter spp. The disease is vectored and transmitted by the Asian citrus psyllid, Diaphorina citri, and the African citrus psyllid, Trioza erytreae, also known as the two-spotted citrus psyllid. It has also been shown to be graft-transmissible.
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