Upgrade your knowledge on CVPD disease (Huanglongbing)

Psyllid Diapohorina Citri Kuw. is a transmitting insect or vector for CVPD that accelerates the spread of this disease in the field. A CVPD vector that containing pathogen L. asiaticus proven is capable to transmit this systemic disease to the healthy citrus trees. If there is no citrus tree that infected by CVPD in the orchard due to disease-free citrus seedlings originated, the presence of transmitting insects is just an ordinary pests that damage shoot bud or young shoots.

In order to have more appropriate control of CVPD vector, the dynamics population of D. citri in the target area that strongly influenced by the development of local environmental conditions should be understood based on the results of monitoring. Monitoring can be done using yellow trap that is installed between the citrus trees as high as half of the plant canopy. The controlling of CVPD transmitting insect will be effective if conducted simultaneously by each member of citrus farmer group. It means that each citrus farmer group is responsible in the controlling of D. citri insects in their respective territories.

D. citri can be effectively controlled with stem wiping/painting methods with a systemic insecticide containing active material imidacloprid or other systemic pesticide of which the effectiveness need to be examined beforehand. The stem painting can be repeated every 2-4 weeks. It also can be done by sprinkling a solution of insecticide with active material tiametoksam 5 grams / liter at a dose of 0.5 liters per tree (4 years old) which applied under the plant canopy, or spraying with insecticide when plants forms buds or shoots. Other insecticides that can be used are listed in Table 1. In contrast to the spraying, the stem painting method would not kill the natural enemies of D. citri as vector of CVPD disease.

The steps for application of stem painting are as follows: (1) Clean stem above joint area till below the main branch is from dirt with a cloth, rubbing is not necessary, (2) paint the stem with brush which dipped in the pure insecticide (not diluted) beforehand, wipe as wide as the diameter of the stem. Stem painting can be done by the tools / special machine. For stem with 18-20 cm girth, use 10-15 ml dose, (3) then water the plant, so that the systemic insecticide that is put beforehand can be distributed immediately to all parts of the plant canopy. The types of insecticides, time and frequency of application are presented in Table 1, Table 2 and Table 3.

Table 1. Active material and how to apply insecticide to control CVPD vector

No Pest Active Material Application

Method

1 Citrus psyllid

(Diaphorina citri Kuw)

§ Imidakloprid

§ Dimethoate

§ Alfametrin/Alfa sipermetrin

§ Teta sipermetrin

§ Profenofos

§ Lamda sihalotrin

§ Metidation

§ Sipermetrin

§ Fenvalerat

§ Fluvalinat

§ Diazinon

§ Bifentrin

Paint

Spray

Spray

Spray

Spray

Spray

Spray

Spray

Spray

Spray

Spray

Spray

Source : Buku Pestisida untuk Pertanian dan Kehutanan, 2002.

Table 2. D. citri time control on the citrus tree which not in production time yet (under 3 years)

Activity 10 11 12 01 02 03 04 05 06 07 08 09
Spraying

(Small canopy)

(Table 1)

x x x x x x x x X
Watering

Tiametoksan

X x x x x x x x x
Stem painting

Imidakloprid

(large canopy)

(x) (x) (x) (x) (x) (x)

Description: x: adjusted based on the results of monitoring; (x): applied if spraying is considered to be ineffective because the canopy become larger.

Table 3. D. citri time control on the productive citrus tree (over 3 years)

Activity

 

1

0

1

1

1

2

0

1

0

2

0

3

0

4

0

5

0

6

0

7

0

8

0

9

Bud
Flower Harvest
Spraying

(Small Canopy)

(Table 1)

x x x (x)
Watering

Tiametoksan

x x (x) x
Stem painting

Imidakloprid

(large canopy)

x x (x) x

Description: x: adjusted based on the results of monitoring; (x): applied if spraying is considered to be ineffective because the canopy become larger and larger.

The research showed that some biological agents are capable to control the vector of CVPD disease in the field effectively, among others are nymphs parasites, ectoparasites Tamarixia radiata and endoparasites Diaphorencyrtus aligarhensis with the level of parasitism in the field respectively 90% and 60-80% in the dry season. Predators Curinus coeruleus preys on eggs and nymphs while Syrphidae usually preys on D. citri eggs.

Entomopathogenic Hirsutella sp. can infect adults CVPD vector in the field up to 60% in the rainy season (Figure 7). In experiment scale, Metarrhizium anisopliae (Methch.) fungi proved to be effective in controlling CVPD transmitting insects.

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