Figure 1.
External symptoms of pine trees infected with B. xylophilus. (a). Beetle feeding wound; (b). Needle discolouration; (c). Needle wilting; (d). Red circle indicates vector beetle oviposition scars.
Figure 2.
Effect of trunk injection treatment of infected pine trees in 2021. a-1 represents the time of shooting (year-month-day): (A). Injection 10 mL, 30 July 2021; (B). Injection 10 mL, 3 August 2021; (C). Injection 10 mL, 6 August 2021; (D). Injection 10 mL, 10 August 2021; (E). Injection 10 mL, 13 July 2021; (F). Injection 10 mL, 3 August 2021; (G). Injection 20 mL, 13 July 2021; (H). Injection 20 mL, 13 July 2021; (I). Injection 10 mL, 10 August 2021; (J). Injection 10 mL, 3 August 2021; (a). Same tree as (A), 29 September 2022; (b). Same tree as (B), 29 September 2022; (c). Same tree as (C), 29 September 2022; (d). Same tree as (D), 29 September 2022; (e). Same tree as (E), 29 September 2022; (f). Same tree as (F), 29 September 2022; (g). Same tree as (G), 29 September 2022; (h). Same tree as (H), 13 September 2022; (i). Same tree as (I), 25 September 2021; (j). Same tree as (J), 23 October 2021. (A–D) are early stage I pine trees, (E) is early stage II pine trees, (F) is middle stage I pine trees, (G–J) are middle stage II pine trees.
Figure 2.
Effect of trunk injection treatment of infected pine trees in 2021. a-1 represents the time of shooting (year-month-day): (A). Injection 10 mL, 30 July 2021; (B). Injection 10 mL, 3 August 2021; (C). Injection 10 mL, 6 August 2021; (D). Injection 10 mL, 10 August 2021; (E). Injection 10 mL, 13 July 2021; (F). Injection 10 mL, 3 August 2021; (G). Injection 20 mL, 13 July 2021; (H). Injection 20 mL, 13 July 2021; (I). Injection 10 mL, 10 August 2021; (J). Injection 10 mL, 3 August 2021; (a). Same tree as (A), 29 September 2022; (b). Same tree as (B), 29 September 2022; (c). Same tree as (C), 29 September 2022; (d). Same tree as (D), 29 September 2022; (e). Same tree as (E), 29 September 2022; (f). Same tree as (F), 29 September 2022; (g). Same tree as (G), 29 September 2022; (h). Same tree as (H), 13 September 2022; (i). Same tree as (I), 25 September 2021; (j). Same tree as (J), 23 October 2021. (A–D) are early stage I pine trees, (E) is early stage II pine trees, (F) is middle stage I pine trees, (G–J) are middle stage II pine trees.
Figure 3.
Effect of trunk injection treatment of infected pine trees in 2022. a-1 represents the time of shooting (year-month-day): (A). Injection 5 mL, 18 July 2022; (B). Injection 5 mL, 11 July 2022; (C). Injection 5 mL, 18 July 2022; (D). Injection 5 mL, 2 August 2022; (E). Injection 5 mL, 11 July 2022; (F). Injection 5 mL, 11 July 2022; (G). Injection 5 mL, 3 July 2022; (H). CK, no injection, 18 July 2022; (a). Same tree as (A), 29 September 2022; (b). Same tree as (B), 29 September 2022; (c). Same tree as (C), 29 September 2022; (d). Same tree as (D), 29 September 2022; (e). Same tree as (E), 29 September 2022; (f). Same tree as (F), 29 September 2022; (g). Same tree as (G), 29 September 2022; (h). Same tree as (H), 29 September 2022. (A–E,H) are early stage I pine trees, (F,G) are early stage II pine trees.
Figure 3.
Effect of trunk injection treatment of infected pine trees in 2022. a-1 represents the time of shooting (year-month-day): (A). Injection 5 mL, 18 July 2022; (B). Injection 5 mL, 11 July 2022; (C). Injection 5 mL, 18 July 2022; (D). Injection 5 mL, 2 August 2022; (E). Injection 5 mL, 11 July 2022; (F). Injection 5 mL, 11 July 2022; (G). Injection 5 mL, 3 July 2022; (H). CK, no injection, 18 July 2022; (a). Same tree as (A), 29 September 2022; (b). Same tree as (B), 29 September 2022; (c). Same tree as (C), 29 September 2022; (d). Same tree as (D), 29 September 2022; (e). Same tree as (E), 29 September 2022; (f). Same tree as (F), 29 September 2022; (g). Same tree as (G), 29 September 2022; (h). Same tree as (H), 29 September 2022. (A–E,H) are early stage I pine trees, (F,G) are early stage II pine trees.
Table 1.
Division of disease stages of pine wilt disease. “+” indicates the degree of pine resin flow, the more “+” means more pine resin, “-” means no pine resin.
Stages of Disease | External Symptoms | Condition of Resin |
---|
Early stage I | maturation feeding evident on twigs, no needle discolouration | ++++ |
Early stage II | maturation feeding evident on twigs, Slight discolouration of needles | +++ |
Middle stage I | maturation feeding evident on twigs, Single twig wilting | + |
Middle stage II | Needle wilt less than 50%, a few oviposition scars | - |
Late stage | Needle wilt greater than 50% or whole plant discolouration or many Monochamus oviposition scars | - |
Table 2.
Suspected and confirmed infected pine trees in 2021 and 2022.
Stages of Disease | Suspected Infected Trees in 21 Years | Infected Trees in 21 Years | Suspected Infected Trees in 22 Years | Infected Trees in 22 Years |
---|
Early stage I | 24 | 4 | 25 | 6 |
Early stage II | 3 | 2 | 2 | 2 |
Middle stage I | 1 | 1 | 1 | 1 |
Middle stage II | 7 | 6 | 4 | 3 |
Late stage | 0 | 0 | 4 | 4 |
Total | 35 | 13 | 36 | 16 |
Table 3.
Total accuracy of the initial diagnosis of each disease stage in 2021 and 2022.
Stages of Disease | Suspected Infected Trees | Confirmed Infected Trees | Accuracy of Initial Diagnosis (%) |
---|
Early stage I | 49 | 10 | 20.4 |
Early stage II | 5 | 4 | 80.0 |
Middle stage | 13 | 11 | 84.6 |
Late stage | 4 | 4 | 100.0 |
Table 4.
The dosage of trunk injection for different confirmed infected pine trees in 2021 and 2022.
Injection Dose/mL | July August 2021 | July August 2022 |
---|
Early Stage | Middle Stage | Early Stage | Middle Stage | Late Stage |
---|
20 | 0 | 2 | 0 | 0 | 4 |
15 | 0 | 0 | 0 | 4 | 0 |
10 | 5 | 3 | 0 | 0 | 0 |
5 | 0 | 0 | 7 | 0 | 0 |
0 (CK) | 1 | 2 | 1 | 0 | 0 |
Table 5.
Analysis of therapeutic effect at different stages of infection.
Stage of Infection | Therapeutic Effect | χ2 | p Value |
---|
Effective | Ineffective |
---|
Early stage | 12 | 0 | 21.439 | p < 0.001 |
Middle stage | 1 | 8 |
Late stage | 0 | 4 |
Table 6.
Residue of 20% emamectin benzoate in the tree after one year of injection.
Injection Dose (mL) | Pesticide Residue (mg/kg) | Mean (mg/kg) | Standard Deviation | Coefficient of Variation/% |
---|
20 | 0.181 | 0.176 | 0.183 | 0.180 | 0.004 | 2.175 |
10 | 0.060 | 0.058 | 0.062 | 0.060 | 0.002 | 3.975 |