Journal Of Crop Protection
Volume:12 Issue: 3, Sep 2023

Early blight caused by Alternaria solani is a prominent tomato, Solanum lycopersicum, disease that destroys a significant part of tomato production worldwide. Cultivating resistant cultivars is notably important in reducing damage caused by early blight disease. Therefore, comprehending the response of different genetic backgrounds to pathogen infection could enhance understanding of the mechanisms involved in plant defense systems against pathogen invasion. In the present study, the differential response of susceptible and resistant tomato genotypes to A. solani was investigated from molecular and physiological aspects. The results showed that soluble sugar content in the resistant genotype increased after pathogen inoculation. Although photosynthetic pigments such as carotenoid, chlorophyll a, and chlorophyll b content decreased in susceptible and resistant genotypes, fluorescence chlorophyll indices differed in resistant and susceptible genotypes. Also, transcription analysis revealed that in the resistant genotype, the expression of SlWRKY1 was 2.58 times more than the control at 48 hpi (hours post inoculation). However, in the susceptible genotype, the expression of the SlNAC1 was 69.12 times more than in control at 24 hpi. The findings of this research provide an improved understanding of tomato plant defense mechanisms against early blight disease.

Biological control represents an effective approach for managing pest populations in horticultural crops, presenting an alternative to the reliance on pesticides. To ensure the successful integration of predators into biological control programs, it is imperative to conduct thorough assessments of how these predators respond to changes in prey density in laboratory settings. In this study, we investigated the functional response of various developmental stages of Hippodamia variegata (Coleoptera: Coccinellidae) when exposed to varying densities of Hyalopterus amygdali (Hemiptera: Aphididae) at 26°C, 65 ± 5% RH, and 16L: 8D h photoperiod. Each treatment was replicated 15 times and conducted on almond leaves placed within Petri dishes. Our findings revealed that all larval stages, as well as adult males and females of the predator, exhibited a type II functional response when presented with different prey densities. We quantified searching efficiency (0.0219, 0.0173, 0.0163, 0.0141, 0.0198, and 0.0128 h-1) and handling times (5.7650, 2.6023, 0.7303, 0.3166, 0.7352, and 0.2920 h) for the first through fourth instar larvae, male and female adults, using Holling's disc equation. Notably, handling times for males were significantly longer than those for females or fourth instar larvae. Nevertheless, no statistically significant differences were observed in the attack rate between fourth instar larvae and either adult females or males. The maximum attack rate (T/Th) for the first to fourth instar larvae, male, and female H. variegata was estimated as 4.163053, 9.222611, 10.52909, 100.2925, 32.64418, and 82.19178, respectively. Consequently, our results indicate that the fourth instar larvae and adult females of H. variegata are recommended for utilization in biological control programs aimed at managing H. amygdali populations.

The cotton shredder bug, Creontiades pallidus Rambur (Hemiptera; Miridae), is a significant pest of cotton, causing extensive damage to cotton leaves and bolls. This study assessed the effectiveness of commercial formulations of phosalone (PHO), thiamethoxam (THX), thiamethoxam + lambda-cyhalothrin (THX + LAM), and spirotetramat (SPI) under field conditions, using both one-time and two-times spray applications. In the one-time spray plots, THX and THX + LAM demonstrated the highest efficacy in reducing C. pallidus populations, as well as mitigating damage symptoms like black spots on cotton bolls and leaves and shredding of cotton blossoms for up to 49 days compared to the control group. However, the effects of SPI and PHO were temporary and diminished after approximately 31 days. When the plots were sprayed for the second time after 30 days, all pesticides significantly decreased pest populations and damage symptoms for up to 49 days. The highest cotton yield in the one-time spray plots was achieved with THX application (323.8 ± 10.62 g cotton/m2), while the SPI-treated plots exhibited the lowest yield (275.7 ± 5.1 g cotton/m2). All THX, THX + LAM, and PHO treatments yielded statistically similar results in the two-times spray plots. Our findings suggest that THX and THX + LAM were the most effective pesticides for controlling C. pallidus populations and mitigating damage symptoms in cotton fields.

This study was aimed to identify secondary metabolites produced by native Trichoderma harzianum isolates and investigate the effect of ethyl acetate (EtOAc) extract of constituents extracted on seed germination and control of Alternaria blight disease. The phytochemical constituents of EtOAc extract of T. harzianum were identified by gas chromatography-mass spectrometry techniques. Also, the effects of foliar application, seed and soil treatments of EtOAc extract and its constituents: benzoic acid, palmitic acid and diisooctyl phthalate, on Alternaria blight disease index was investigated. All T. harzianum isolates were able to significantly reduce the mycelial growth of A. alternata by producing volatile and non-volatile metabolites. The major constituents of the EtOAc extract were 2-phenylethanol (14.36%), palmitic acid (12.07%), diisooctyl phthalate (11.23%), which have antifungal effects against A. alternata. The lowest values of minimum inhibitory concentration (MIC) of the EtOAc extract and its main constituents were in the range of 1,044-3,970 μg. mL-1. The MIC value of the benzoic acid (1,044 μg. mL-1) against A. alternata was lower than iprodione-carbendazim (1,391 μg. mL-1) and mancozeb (1,600 μg. mL-1). Combining benzoic acid with diisooctyl phthalate induced a synergistic activity against A. alternata and in combination with palmitic acid caused an additive effect. Seed treatment with EtOAc extract and/or benzoic acid significantly reduced the development of Alternaria blight disease of Cumin compared to foliar and soil applications. The seed treatment with EtOAc extract and palmitic acid significantly improves the seed germination by 11.34% and 9.57%, respectively. The findings provide new perspectives on the effect of the secondary metabolites produced by native T. harzianum isolates on the quality characteristics of seeds and the rate of soil-borne and seed-borne diseases progression caused by A. alternata.

The European grapevine moth, Lobesia botrana (Denis and Schiffermueller) (Lepidoptera: Tortricidae), is a significant pest causing economic damage to vineyards worldwide. In this research, the cold tolerance of the pupae and its relationship with diapause was investigated at 23 ± 0.5 °C, 70 ± 5% RH, and LD 12:12 h. One-day-old eggs were transferred to LD 12:12 h to induce diapause at the pupal stage. Diapausing pupae exhibited a mean supercooling point (SCP) of -24.35 °C, whereas in the non-diapausing pupae (23 ± 0.5 °C, 70 ± 5% RH, LD 16:8 h), it was -23.06 °C, with no significant difference between the two groups. Furthermore, diapausing pupae demonstrated significantly higher cold tolerance (LT50 of -14.43 °C) than non-diapausing pupae (LT50 of -3.33 °C). Diapausing pupae tolerated subzero temperatures without significant changes in the SCP, tolerating 11 °C lower than control pupae due to the short daylength alone. Our results suggest that the diapause state and cold hardiness of L. botrana are independent of changes after SCP, and the insect employs a freeze-intolerant strategy to overcome subzero temperatures. Cold acclimation at -5 and -10 °C for 72 h induced a significant decrease in the SCP of diapausing pupae, while a 72-h cold acclimation had no notable impact on the SCP of non-diapausing pupae. These findings provide valuable insights into the survival mechanisms of the European grapevine moth under cold conditions and diapause-related adaptations.

This study aimed to assess the effect of a time gap between adding adjuvant and herbicide to the tank on hard-water antagonism of trifloxysulfuron under greenhouse conditions. Treatments consisted of herbicide dose (0, 0.75, 1.5, 3, 6, and 12 g ha-1), spray carrier (distilled water ± 600 mg MgCl2, CaCl2, and FeCl3 L–1), the order of adding adjuvant and herbicide to the spray carrier (herbicide alone, the addition of 20 g ammonium sulfate L-1 or 300 mg citric acid L-1 15 min before, at the same time, and 15 min after adding trifloxysulfuron to the spray carrier). The dry matter of velvetleaf was regressed over the doses of trifloxysulfuron to obtain herbicide doses in which 50 and 90% velvetleaf control occur (ED50 and ED90, respectively). The presence of Mg2+, Ca2+, and Fe3+ in the spray carrier increased the ED50 from 2.41 to 5.07, 7.65, and 9.78 g a.i. ha-1 and the ED90 from 5.88 to 16.56, 28.48, and 28.19 g a.i. ha-1, respectively, indicating a hard-water antagonism of trifloxysulfuron as Fe3+ = Ca2+ > Mg2+. Generally, the best order was adding adjuvants 15 min before adding trifloxysulfuron to the tank. It could completely overcome the hard-water antagonism of trifloxysulfuron. In contrast, the order of adding adjuvants 15 min after adding trifloxysulfuron to the tank had no significant effect on overcoming the hard-water antagonism of trifloxysulfuron, resulting in additional costs for farmers.

Dragon’s head Lallemantia iberica, currently is grown as an oilseed crop in dry areas of Iran. In 2019, symptoms including seedling damping-off, yellows, and wilt were observed on the plants in a commercial field in Maragheh province, Iran. Based on the morphological and molecular characters, the fungus isolated from symptomatic plants was identified as Fusarium acuminatum. The pathogenicity of the fungus was confirmed through inoculation of the host plant. Subsequently, Koch’s postulates were fulfilled by re-isolation of the same fungus from the inoculated symptomatic plants. This is the first report of Fusarium wilt disease occurring in Dragon’s head in Iran and worldwide.

This study was conducted to quantify the germination response of Capers Capparis spinosa L. to temperature and water potential. The seeds were germinated at seven temperatures (5, 10, 15, 20, 25, 30, and 35 °C) and six water potentials (zero, -0.3, -0.6, -0.9, -1.2 and -1.5 MPa). Increased water potential and temperature decreased germination percentage and increased germination time. The results revealed that the dent-like function (RMSE = 0.24, R2 = 0.82, and r = 0.86) is suitable for describing the response to temperature and water potential. Based on the dent-like model base, optimum and ceiling temperatures were estimated as 8.81 to 11/13, 21.30 to 24.88, and 35.22 to 37.55 °C, respectively. Biological hours for the control treatment (zero potential water) were calculated as 52.11 hours. The hydro time constant for SSG (θH), the middle value for the base water potential (Ψb(50)), the standard deviation in base water in the water potential (σyb), and the thermal time constant for SSG (θT) spanned the values of 0.63–243.48 MPa h, −0.3–2.59 bar and 343.3–1344.3 °C h, respectively. The hydrothermal time parameters were 445.12 bar °C h, −2.274 MPa, and 8.28 °C for θHT, and Ψb(50), Tb in temperatures and water potentials, respectively.