Development of sooty moulds in mango orchards in relation to weather parameters and major sucking pests

Abstract

Aim: Methodology:Results: Interpretation:Sooty moulds proliferate on mango foliage, subsisting on the honeydew created by sucking pests. It reduces photosynthetic area of tree. Factors affecting the development of sooty moulds on mango trees was studied for three consecutive seasons (2013, 2014 and 2015).Data were recorded at weekly interval from trees of mango cv. of 20-35 year age selected with planting at 7.5 m × 7.5 m to 10 m × 10 m distances at 22 different locations in Lucknow district. Sooty moulds incidence and severity data were analyzed for relationship with sucking pest incidence and weather data.Sooty moulds incidence and severity was found to vary across the seasons. Peak incidence (28.8 %) of sooty mould was recorded during the 11 Standard Meteorological Week (SMW) with peak severity (14.2 %) during 17 SMW of the year 2013. During the year 2014, peak incidence (27.8) and severity (15.6 %) of sooty mould was recorded during 40 SMW. Similarly, peak incidence (42.5 %) and severity (27.5 %) of sooty mould was recorded at 25 SMW during the year 2015. The higher incidence and severity of sooty mould was recorded during the year 2015 compared to 2014 and 2013. Mango hoppers peak incidence was observed during 13 , 19 and 23 SMW during the year 2013, 2014 and 2015. Whereas, the scale insect peak incidence was recorded during 9 , 39 and 14 SMW during the year 2013, 2014 and 2015 respectively. Scale insect incidence had significant positive correlation with the sooty mould incidence (r = 0.65) and severity (r =0.60). Among the weather parameters, only rainfall had positive correlation with incidence (r = 0.35) and severity (r = 0.37) of sooty moulds.Step wise regression analysis showed that the hopper and scale insect incidence could influence the disease incidence upto 45 % and severity pto 39 %. When significant weather factor rainfall was taken into consideration, the corresponding values increased to 51 % and 47 %. However, scale insect incidence had exponential relationship with the i n c i d e n c e a n d severity of sooty mould.The studies indicated that scale insect, hopper and rainfall together play a vital role in the d e v e l o p m e n t o f mango sooty mould. O t h e r w e a t h e r factors did not have s i g n i f i c a n t relationship with s o o t y m o u l d development, but their indirect effect cannot be ruled out.

Effect of sap-feeding insects, plant characteristics, and weather parameters on sooty moulds in the temperate zone

“…In tropical SMBs on mango, SFI incidence significantly influenced SMB incidence up to 45% (Shukla and Gundappa 2017), and SFIs often occurred simultaneously with the SMB (Dhami et al 2013;Shukla and Gundappa 2017), which could not be confirmed in this current study for the temperate region on host plants with deciduous leaves. However, despite the large time gap between the main season of SFIs in spring and the main season of SMB in late summer and fall, trees infested by SFIs on four or more observation dates had significantly more SMBs (3.7-fold).…”

“…In some studies on symptomless leaves without visible SMBs, variations in fungal communities were investigated and mainly interpreted as directly linked with climatic weather conditions, such as temperature, precipitation, relative humidity, and wind speed (Lee and Hyde 2002;Talley et al 2002;Gomes et al 2018) without a link to SFI occurrence. There was one long-term study in mango orchards that confirmed a strong correlation between SFIs and SMBs (Shukla and Gundappa 2017) in combination with weather parameters. However, since this study was carried out on a single evergreen host plant species in the tropics, no conclusions can be drawn about the influence of host plant characteristics, especially on deciduous leaves in the temperate zone.…”

“…In the tropics, SMB occurs throughout the year on evergreen host plant leaves (Shukla and Gundappa 2017), while in the temperate region, SMB can only be observed on host plants with deciduous leaves toward the end of the growing season. However, many weather parameters are similar in spring and fall and, therefore, cannot be the main reason for the late occurrence of SMB.…”

“…Most studies on SMBs examined variables that alter the composition of the fungal community but not which variables lead to an SMB on host plants in the first place. Studies on multitrophic interactions in the phyllosphere, concerning SMB and sap-feedings insects, include usually just one (Stadler et al 1998;Mühlberg and Stadler 2005;Perez et al 2009;Shukla and Gundappa 2017) or a few host plant species (Dhami et al 2013) and do not provide conclusions about SMB-promoting host plant characteristics. The occurrence, structure, and succession of epifoliar fungal communities are known to underlie seasonal variations (Cabral 1985;Lee and Hyde 2002;Osono 2008), but data on SMBs were usually sampled during a very short time period and, therefore, disregard seasonal variations in SFI dynamics (Perez et al 2009;Dhami et al 2013).…”

Discrete approximate iterative method for fuzzy investment portfolio based on transaction cost threshold constraint

“…However, in reality an investor can re-distribute their own assets and so maintain a multiple-period investment strategy. The singleperiod investment portfolio can definitely be expanded to a multiple-period one [16,17,[17][18][19][20][21]. For instance, Mossin, Hakansson, Li, Chan and Ng, Li and Ng, Calafiore, Zhu etc., Wei and Ye, Gupinar and Rustem, Yu etc., Clikyurt and Ozekici.…”