Correction of zinc and boron deficiencies and control of phytophthora root rot of avocardo by trunk injection

1991 ◽  
Vol 31 (4) ◽  
pp. 575 ◽  
Author(s):  
AW Whiley ◽  
KG Pegg ◽  
JB Saranah ◽  
PW Langdon
Keyword(s):  
Root Rot ◽  
Growing Season ◽  
Zinc Nitrate ◽  
Threshold Concentration ◽  
Persea Americana ◽  
Critical Threshold ◽  
Phytophthora Root Rot ◽  
Zinc Concentrations ◽  
Trunk Injection ◽  
And Control

Phosphonate at 3 concentrations (7.5, 10 and 20%) was injected into the trunks of avocado (Persea americana Mill.) trees showing advanced symptoms of canopy decline caused by phytophthora root rot. All formulations of phosphonate and potassium phosphonate, including the lower rates of 7.5 and 10%, successfully controlled root rot and resulted in improved tree health. The 7.5% phosphonate treatment permitted the formulation of chemically compatible mixtures containing zinc and boron which, when trunk-injected, increased the concentrations of these nutrients in mature summer-grown leaves. Phosphonate formulations containing 17% zinc chelate or 10% zinc nitrate and injected twice during a growing season, at 15 mL/m canopy diameter, increased leaf zinc concentrations above the critical level of 30 mg/kg DM. However, the inclusion of zinc chelate in formulations substantially increased the time of uptake of the injection compared with the formulation containing zinc nitrate. Phosphonate formulations with 0.9% boron, injected twice during a growing season at 15 mL/m canopy diameter, improved leaf boron concentrations, but they failed to reach the critical threshold concentration of 50 mg/kg DM.

Comparison of phosetyl-Al, phosphorous acid and metalaxyl for the long-term control of Phytophthora root rot of avocado

1987 ◽  
Vol 27 (3) ◽  
pp. 471 ◽  
Author(s):  
KG Pegg ◽  
AW Whiley ◽  
PW Langdon ◽  
JB Saranah
Keyword(s):  
Root Rot ◽  
Phytophthora Cinnamomi ◽  
Phosphorous Acid ◽  
Growing Season ◽  
Phytophthora Root Rot ◽  
The Third ◽  
Consecutive Season

Avocado trees affected by root rot caused by Phytophthora cinnamomi Rands recovered rapidly when given injections into the trunk of phosetyl-A1 or phosphorous acid. Injected trees had greater yields(47.9-67.5 v. 4.3 kg fruit per tree) and lower leaf chloride levels (0.8-2.4 v. 4.2%, w/w) than controls in the third season after starting treatment. Phosphorous acid residues (21-83 mg kg-1) were detected in fruit from injected trees. Metalaxyl applied to the soil twice each growing season successfully controlled root rot for the first 2 seasons, but there was a significant resurgence of decline symptoms after the third consecutive season of use.

scholarly journals 14C-Photosynthesis Partitioning in Avocado Trees as Influenced by Shoot Development

HortScience ◽  
1993 ◽  
Vol 28 (8) ◽  
pp. 850-852 ◽  
Author(s):  
Anthony W. Whiley ◽  
Bruce Schaffer
Keyword(s):  
Root Rot ◽  
Liquid Scintillation ◽  
Phytophthora Cinnamomi ◽  
Management Strategies ◽  
Persea Americana ◽  
Plant Tissues ◽  
Quiescent State ◽  
Assimilation Rate ◽  
Phytophthora Root Rot ◽  
C Partitioning

The influence of shoot age on 14C partitioning in potted avocado (Persea americana var. americana Mill.) trees was determined. The oldest leaf of actively growing shoots and the youngest leaf of previously matured shoots were exposed to 14CO2 18 and 34 days after budbreak (DABB) of new shoots. At these times, treated leaves had a positive net CO2 assimilation rate and, therefore, were considered to be net C exporters. Sixteen days after 14C exposure, separate plant tissues were harvested, dried, weighed, and oxidized. The percentage of 14C in each tissue was determined by liquid scintillation spectrometry. Photoassimilates were translocated acropetally and basipetally from all treated leaves. However, at 18 DABB, developing leaves of actively growing shoots seemed to be the strongest sink for C assimilated by the oldest leaf of these shoots, whereas the roots were the strongest sink for C assimilated by the youngest leaf of the previously matured shoots. By 34 DABB, roots were the strongest sink for C assimilated by leaves of new and previously matured shoots. These data are useful in developing improved management strategies for controlling phytophthora root rot (incited by Phytophthora cinnamomi Rands) in avocados by systemic phosphonate fungicides translocated in the photoassimilate pathway. Thus, phosphonates should be applied after shoots have matured and most of the canopy is in a quiescent state for maximum translocation to the roots.

Changing sink strengths influence translocation of phosphonate in avocado (Persea americana Mill.) trees

1995 ◽  
Vol 46 (5) ◽  
pp. 1079 ◽  
Author(s):  
AW Whiley ◽  
PA Hargreaves ◽  
KG Pegg ◽  
VJ Doogan ◽  
LJ Ruddle ◽  
...  
Keyword(s):  
Growing Season ◽  
Phloem Transport ◽  
Final Concentration ◽  
Persea Americana ◽  
Sink Strength ◽  
Tree Phenology ◽  
Trunk Injection ◽  
Three Stages ◽  
Hass Avocado ◽  
Rate Of Accumulation

Translocation of phosphonic acid (H3PO3) in cv. Hass avocado trees was studied after trunk injection with 20% H3PO3, formulated as potassium phosphonate, at three stages of tree phenology during the growing season. Initially, translocation was solely acropetal in the xylem, and H3PO3was detected in the leaves 24 h after treatment. Several days after injection, H3PO3concentration in the bark of trunks and in roots increased, indicating basipetal phloem transport of H3PO3from leaves. The rate of accumulation and the final concentration of H3PO3in the roots were directly related to the sink strength of the shoot at the time of injection. For example, trunk injection at the beginning of spring growth flush, when renewal shoots were strong sinks, resulted in low H3PO3root concentrations (<9 8g gfw-1) which peaked about 45 days after treatment. When potassium phosphonate was injected after the transition of spring-grown shoots from sinks to sources, or at summer shoot maturity, root concentrations of H3PO3increased to >25 8g gfw-1 by 30 days after treatment. These results suggest that strategic timing of injections according to phenological events may greatly improve fungicide efficacy when targeting specific organs for protection.

Influence of Phytophthora root rot on mineral nutrient concentrations in avocado leaves

1987 ◽  
Vol 27 (1) ◽  
pp. 173 ◽  
Author(s):  
AW Whiley ◽  
KG Pegg ◽  
JB Saranah ◽  
PW Langdon
Keyword(s):  
Root Rot ◽  
Potassium Hydroxide ◽  
Phytophthora Cinnamomi ◽  
Chloride Content ◽  
Persea Americana ◽  
Mineral Nutrient ◽  
Nutrient Concentrations ◽  
Phytophthora Root Rot ◽  
Zinc Levels ◽  
Chloride Concentrations

Leaf nutrient concentrations were measured in avocado trees (Persea americana Mill. cv. Fuerte) which were recovering from root rot (Phytophthora cinnamomi Rands) following treatment with fungicides. Trees with visible Phytophthora root rot symptoms had higher leaf chloride concentrations in 4- month-old leaves (0.35%) which increased to 0.5% in 8-month-old leaves, compared with chloride concentrations in leaves from trees that had regained health of 0.13-0.27% and 0.09-0.24% in 4- and 8-month-old leaves respectively. Leaf tip and marginal burn symptoms in untreated control trees were present in leaves with 0.5% chloride content. Trees which were previously infected, but had regained health, had higher leaf concentrations of nitrogen (2.86-3.02%), phosphorus (0.18-0.19%), sulfur (0.24-0.27%), zinc (33.2 mg kg-1) and boron (13.4-17.7 mg kg-1) than leaves on those trees showing severe root rot symptoms (2.59% nitrogen, 0.16% sulfur, 24.4 mg kg-1 zinc, and 8.1 mg kg-1 boron). Fungicidal treatments, which included the injection of phosphite, potassium hydroxide and zinc sulfate into trees, did not contribute significantly to leaf phosphorus, potassium or zinc levels.

scholarly journals The system of plant protection of cucumbers from root rot in greenhouses

2019 ◽  
pp. 12-15
Author(s):  
K. Balvas-Hremiakova
Keyword(s):  
Technical Efficiency ◽  
Root Rot ◽  
Plant Protection ◽  
Growing Season ◽  
Integrated Approach ◽  
Protective Properties ◽  
Biological Preparation ◽  
Vegetable Products ◽  
Spraying Plants ◽  
And Control

Goal. To study the antagonistic and protective properties of the biological preparation Trichodermin, p (titer 1.5 × 108 spores / ml) based on the producer strain Trichoderma lignorum CK in relation to the complex of pathogens of root and root rot (Fusarium oxysporum Sh, F. solani sp. Cuarbitae, F. moniliforme Sh, F. culmorum Sacc, Fusarium solani App. et Wr) indoor cucumbers to protect crops throughout the growing season. Methodology. The effectiveness of the biological product was evaluated in greenhouses in the Kiev region in 2016—2018. On crops of cucumbers (hybrid Courage F1) with various methods of application — seed treatment and spraying of plants. To assess the damage of cucumber plants by root rot, we used data on the spread and development of the disease in the experimental and control plots, the counts were carried out on a four-point scale VIZR in the modification of V.F. Peresypkina and V.M. Pidoplichko. Results. As a result of the studies, the high technical efficiency of the use of biological preparations in the crops of cucumbers in greenhouse agrocenoses was established. When treating seeds before planting with a 1% solution of the biological preparation Trichodermin, p based on the producer starch Trichoderma lignorum CK, not one seedling died from root rot, but at the 45th and 65th stages of development according to the BBCH scale, technical efficiency decreased accordingly to 68.3 and 59.5%. Repeated application of the biological preparation Trichodermin, p with a consumption rate of 10 l / ha by three sprays during the growing season in the development phase 74—86 on the BBCH scale showed high technical efficiency (85.3%) in protecting plants against root rot. Findings. An effective method of protecting cucumber crops in closed ground from root rot is an integrated approach to biocontrol — treating seeds before planting and spraying plants with the biological preparation Trichodermin P, which showed a technical efficiency of 85.3%. Monitoring the development of root rot in a critical period of development allows you to reduce root rot damage by 2.2 times and additionally obtain up to 7.7 kg / m2 of vegetable products.

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