Objective 1: Investigate the efficacy of bactericides treatments for preventing new infections for young citrus trees protection.
Hypothesis: Bactericidal treatment will protect young trees from CLas colonization.
Initial leaf samples were collected prior to treatments to evaluate CLas titers in the uninfected trees.
We applied bactericide treatments from May through September. CLas titer was monitored in leaf tissue in response to antibiotic treatments using quantitative real-time PCR analysis. In this report, the results of CLas-infection rate in citrus leaves from May and June is described. Currently, citrus leaves tissue samples from July through September are being processed to analyze the CLas-infection rate.
*Trees were considered CLas-infected (positives) when CT values were below 35.
1. Antibiotics (monthly rotation): Prior to bactericide application (May), 15% of trees (20 trees/treatment) were CLas positive (Ct<35). After the bactericide application (June), 35% of trees were CLas positive (Ct<35).
2. Antibiotics (quarterly rotation): Prior to bactericide application (May), 100% of trees were CLas negative (Ct>35). After bactericide application (June), 40% trees were CLas positive (Ct<35).
3. Negative Control (insecticide + Tree defender exclusion netting): Prior to bactericide application (May), 100% of trees were CLas negative (Ct>35). After the bactericide application (June), 45% trees were CLas positive (Ct<35).
4. Positive Control (insecticide only): Prior to bactericide application (May), 100% of trees were CLas negative (Ct>35). After the bactericide application (June), 5% trees were CLas positive (Ct<35).
Counting of ACP adults using taps was conducted bi-weekly from May through September, presence of other life stages such as eggs and nymphs were scouted visually. Preliminary results showed a low ACP population in citrus locations due to the active vector management performed by farm manager. As consequence, no ACP adults were collected to analyze the CLas-infection rate using quantitative real-time PCR analysis. The overall number of eggs and nymphs were low or undetectable in citrus trees from May to September. Also, to determine the effect of citrus vegetative growth (flush-like structures) in CLas-infection rate, 1 ft.3 was used to count the number of flush-like structures per tree. Results showed that the presence of flush-like structures incremented from May to July and decreased in September.
Objective 2. Determine the effect of bactericides application frequency on Las infection of citrus.
Hypothesis: Bactericidal treatment will reduce CLas infection in mature trees.
We applied bactericide treatments from May through September. CLas titer was monitored in leaf tissue in response to antibiotic treatments using quantitative real-time PCR analysis. In this report, the results of CLas-infection rate in citrus leaves from May and June is described. Currently, citrus leaves tissue samples from July through September are being processed to analyze the CLas-infection rate.
*Trees were considered CLas-infected (positives) when CT values were below 35.
1. Antibiotics (monthly rotation): Prior to bactericide application (May), 100% of trees (20 trees/treatment) were CLas positive (Ct<35). After the bactericide application (June), 100% of trees were CLas positive (Ct<35). Although positive, bacterial titers declined in trees receiving antimicrobial treatments.
2. Antibiotics (quarterly rotation): Prior to bactericide application (May), 100% of trees were CLas positive (Ct<35). After the bactericide application (June), 100% of trees were CLas positive (Ct<35).
3. Positive Control (insecticide only): Prior to bactericide application (May), 100% of trees were CLas positive (Ct<35). After the bactericide application (June), 100% of trees were CLas positive (Ct<35).
Counting of ACP adults using taps was conducted bi-weekly from May through September, presence of other life stages such as eggs and nymphs were scouted visually. Preliminary results showed high ACP populations in treatments from May to August, excepting for June. The number of eggs and nymphs were not collected during May and first collection of June. However, populations increased from late June to August and reached high population levels. Currently, ACP adults that were collected bi-weekly are being processed to analyze the CLas-infection rate using quantitative real-time PCR analysis. Also, to determine the effect of citrus vegetative growth (flush-like structures) in CLas-infection rate, 1 ft3 was used to count the number of flush-like structures per tree. Flush was not collected during May and June. However, results showed that the presence of flush was high in July and August.