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Pear is one of the most important commercial crops of India. It is grown in northwestern states and hills of the country. India is the 9th largest pear producer in the world. Its cultivation area increased from about 19000 ha in 1991 to 42000 ha in 2019, with 2.2 times of increase over 28 years. In India, pears cultivated from foothills to high hills experience about five hundred to thousand five hundred chilling hours throughout the year. In India, pear occupies the third place for temperate fruits by area of cultivation and production quantity. The area with pear cultivated is steadily increasing in India. It is mainly grown in northern states of Jammu and Kashmir, Himachal Pradesh, Uttarakhand, Punjab, and in south India (Tamilnadu state). The region of north-eastern hills, comprising of states of Arunachal Pradesh, Nagaland, Mizoram, Meghalaya, and Sikkim, also grows pear on a limited scale. Although northwestern and eastern hills of India provide a favorable climatic condition for growing a wide range of pears, cultivation and production of pears remain challenging due to pests and diseases. In this article, we discussed the current status of pear production and major common insects and pests in pear-growing regions of India.

The current social demand for organic, sustainable, and eco-friendly approaches for farming, while ensuring the health and productivity of crops is increasing rapidly. Biocontrol agents are applied to crops to ensure biological control of plant pathogens. Research on the biological control of white root rot disease caused by a soil-borne pathogen, Rosellinia necatrix, is limited in pears compared to that in apple and avocado. This pathogenic fungus has an extensive host range, and symptoms of this disease include rotting of roots, yellowing and falling of leaves, wilting, and finally tree death. The severity of the disease caused by R. necatrix , makes it the most harmful fungal pathogen infecting the economical fruit tree species, such as pears, and is one of the main limiting factors in pear farming, with devastating effects on plant health and yield. In addition to agronomic and cultural practices, growers use chemical treatments to control the disease. However, rising public concern about environmental pollution and harmful effects of chemicals in humans and animals has facilitated the search for novel and environmentally friendly disease control methods. This review will briefly summarize the current status of biocontrol agents, ecofriendly methods, and possible approaches to control disease in pear orchards.

White root rot disease, caused by

The optimal harvest date for ‘Whasan’ pears (Pyrus pyrifolia ‘Whasan’), which is difficult to predict, is currently determined on the basis of field observations of fruit quality. To create better models for predicting pear maturation, we utilized flowering period data from the Pear Research Institute, South Korea; commercial harvest data; and daily meteorological information from 2007 to 2011 to assess five temperature-related parameters for inclusion in the models: (1) daily mean temperature; (2) daily maximum temperature; (3) daily minimum temperature; (4) average of the daily mean temperature and daily maximum temperature; and (5) average of the daily mean temperature, daily maximum temperature, and daily minimum temperature. We used these parameters and the minimum coefficient of variation method to estimate the base temperature and construct five temperature-based models for predicting harvest date. Data from 2015 to 2016 were used to evaluate the performance of these models, as assessed by average absolute deviation, average squared error, and average absolute percentage error. Using the average of the daily mean and maximum temperatures as the variable input temperature and 9.4 °C as the base temperature, we obtained the most accurate prediction of the optimal pear harvest date. Our model indicates that the optimal harvest date for ‘Whasan’ pear occurs at 2370 accumulated growing-degree days after full bloom.

Although Taiwan produces small fruits on a small scale, it is famous for its production techniques and systems. Only two types of small fruits are economically produced in Taiwan: the grape and strawberry. Four other types (the mulberry Morus alba L., the bayberry Myrica rubra Sieb. et Zucc., the Indian gooseberry Phyllanthus emblica L., and the kiwifruit or Chinese gooseberry Actinidia chinensis Planch. var. setosa and A. deliciosa Ferg.) have production areas of less than 100 ha. Taiwan has been developing production techniques for fruits such as the blueberry. In 2017, Taiwan had production areas of 2,828.6 ha for grapes, 500.33 ha for strawberries, 67.56 ha for mulberries, 31.17 ha for bayberries, and 14.19 ha for kiwifruit. The development of new small fruit crops demands new culture methods and strategies. It is important to breed or select new small fruits from the native germplasm when introducing new foreign varieties. Some special conditions, such as breeding the blueberry plant with a short chilling requirement, are needed. Further, new culture systems such as year-round production for grape, mulberry, and strawberry have been tried. Although Taiwan has cultivated grapes for wine production for over 40 years, new grape cultivar breeding programs for wine production have been introduced.

The foraging preferences of Apis mellifera for flower depend on the content of sugar and amino acid in nectar. To determine the factor in nectar that attracts honeybee in field, we investigated the foraging rate of honeybee, fruit set, relationship between the foraging behavior of honeybee and contents of nectar in different Asian pear cultivars (‘Niitaka’ and ‘Whangkeumbae’), which do not produce pollen. The foraging rate of honeybee on ‘Whangkeumbae’ was 2 times higher than that on ‘Niitaka’ and the fruit set of ‘Whangkeumbae’ was 1.5 times higher than that of ‘Niitaka’. ‘Whangkeumbae’ exhibited 3.7 times higher nectar secretion than ‘Niitaka’. The total sugar content in the nectar of ‘Whangkeumbae’ was 1.1–1.7 times higher than that in the nectar of ‘Niitaka’, and this difference was significant. Furthermore, the content of glucose, fructose, and sucrose in the nectar of ‘Whangkeumbae’ was higher than that in the nectar of ‘Niitaka’. In particular, the content of sucrose in ‘Whangkeumbae’ was 1.3–3.2 times higher than that in ‘Niitaka’; sucrose is known to be the most preferred sugar by honeybee. Among the 20 amino acids detected in both cultivars, the content of Nine amino acids was significantly different. The content of phenylalanine and glycine (which are preferred by honeybee) in ‘Whangkeumbae’ was 1.4–2.4 times higher than that in ‘Niitaka’. In contrast, the content of asparagine (which is not preferred by honeybee) in ‘Niitaka’ was 1.1–2.4 times higher than that in ‘Whangkeumbae’. Among the sugars in nectar, sucrose exhibited the highest relationship with the number of foraging bees, followed by glucose and fructose. Among the amino acids, phenylalanine presented the highest correlation with the number of foraging bees, followed by glycine and alanine. The results suggest that honeybees prefer ‘Whangkeumbae’ over ‘Niitaka’ because of the difference in the amino acid and sugar content in the nectar of pear cultivars.

The efficacy of different control techniques against the large black chafer, Holotrichia parallela Motschulsky (Coleoptera: Scarabaeidae), in organic pear (Pyrus pyrifolia) orchards was evaluated. In this study, field trials were conducted in three locations in Korea—Naju, Hampyeong, and Boseong—to evaluate different techniques to suppress these beetles. Pheromone traps, bio-insecticides (Hongmengye and Melchungdaejang), and a combination of the two were applied as treatments. In Naju, Hampyeong, and Boseong, the highest number of adult H. parallela were caught in the control plots (n=45, n=39, and n=20, respectively), while the fewest were caught in the pheromone plus bio-insecticide plot (n=19) in Naju and in the combined treatment plot in Hampyeong (n=10). In Naju, the greatest leaf damage was observed in the control (66%), and in all locations (Naju, Boseong, and Hampyeong), the least damage occurred in the combined treatment plots (42%, 36%, and 24%, respectively). Regarding the tree canopy, the greatest leaf damage was observed in the upper canopy, and less damage was observed in the lower canopy. These results demonstrate that the combination of sex pheromone traps and bio-insecticides can be used to manage H. parallela in organic pear orchards.

Thrips are one of the insect pests of persimmon (Diospyros kaki Thunb.) in the major production areas of astringent persimmon in Korea. We surveyed astringent persimmon orchards in the Damyang, Sangju and Cheongdo regions of Korea to determine thrips species composition and abundance. Orchards sprayed with either organic or conventional pesticides were sampled over the course of one flowering season, using yellow sticky traps to determine if this is a suitable method for monitoring thrips populations, and to determine thrips species composition and abundance. Eight thrips species were captured on yellow sticky traps in both the tree canopy and ground cover: Ponticulothrips diospyrosi Haga et Okajima, Scirtothrips dorsalis (Hood), Frankliniella occidentalis (Pergande), F. intonsa (Trybom), Thrips tabaci (Lindeman), T. hawaiiensis (Morgan), T. coloratus (Schmutz) and T. palmi (Karny). In all regions, F. occidentalis and F. intonsa dominated in both organic and conventional orchards. S. dorsalis, F. occidentalis, F. intonsa and T. hawaiiensis were found in persimmon flowers, with S. dorsalis the dominant thrips. Significantly more S. dorsalis were captured from flowers in the lower and middle canopy than in flowers from the upper canopy. Fruit damage was also significantly higher in fruit from the lower canopy than in fruit from the middle and upper canopy.

In this study, a portable, non-destructive tester, integrating near-infrared (NIR) spectroscopy, was developed to determine the maturity of Asian pears. In addition, regression analysis was conducted for mature Manpungbae pears using the partial least squares regression model with the Brix value of Asian pears in a wavelength range of 710–930 nm, and the standard error of calibration or standard error of prediction (SEC/SEP) of 0.41–0.43 °Brix and relative standard error of calibration or relative standard error of prediction (rSEC/rSEP) = 0.91–0.92 were observed, indicating excellent prediction performance with no dependence on pretreatment conditions. Furthermore, the reliability of the developed Brix determination model was confirmed using Manpungbae, Wonhwang, Chuhwangbae, and Niitaka pears, and SEP, rSEP, and bias values of 0.29–0.33 °Brix, 0.90–0.96, and 1.67E−04, respectively, were observed, indicating high reliability. Hence, the construction of a Brix determination model by the accumulation of absorbance for several varieties of pears in each harvest period is expected to determine optimum harvest times via the measurement of the Brix values at full maturity regardless of the variety.

In this paper, we introduce a new method for knowledge sharing. We call it shared rules. In the shared rules service, users or organizations represent their knowledge in Rule Interchange Format (RIF) rules and post them on the Web. The rules are shared with everyone and infer useful information for each user. This service can be regarded as implementing a single global rule-based expert system on the Web, and it has an uncertainty problem in rule reasoning, as in existing expert systems. In the existing rule-based systems, the uncertainty problem can be mostly resolved at the design and development stage, but in the shared rules service, the problem inevitably arises because rules are freely written and shared by various users. In this paper, we analyze the uncertainty problem and explain that the problem can be resolved using existing methods.

Time-specific responses of flower bud differentiation were investigated in ‘Shinko’ (Pyrus pyrifolia Nakai) pear grown at different altitudes from July through December 2013 to determine their suitability as scions in a top-grafting system. Flower bud initiation and bud necrosis were monitored on each of three sections of one-year-old shoots: terminal, middle, and basal. Flower bud differentiation s tarted in September in the highlands of the Lishan area, and in J uly in the lowlands of the Zhoulan area. In Lishan, flower bud differentiation was higher in the middle and basal segments; during leaf fall, however, flower bud differentiation occurred rapidly in the terminal segment. In Zhoulan, flower buds began to differentiate from the terminal section of the shoot, and severe flower bud necrosis was noted. In July, flower buds developed normally; however, in early August, some of the buds at the basal segment showed browning. During leaf fall, some flower buds showed symptoms of necrosis with rapid and complete browning. Flower bud necrosis began at the basal segment and progressed rapidly towards middle and terminal sections. Before leaf fall, flower buds fell off when scales swelled. The terminal and middle parts of the current-year shoots, with some flower buds, collected in October or later from the Lishan area could be used as scions for top-grafting of ‘Shinko’ pear. Each grafting scion was a 3-5 cm shoot with one flower bud. These results suggest that scions from the terminal and middle segments of stems of ‘Shinko’ pear from the Lishan area can be used as scions whereas those from Zhoulan area show necrosis and might not be suitable as scions.

The popularity and demand of early season ‘Wonhwang’ pear fruit are getting increased due to premium fruit quality. However, numerous physiological disorders can be developed after harvest and during short-term storage. The objective of the study was aimed to evaluate the effectiveness of gibberellic acid4+7 (GA4+7) at fruitlet stage, 1-methylcylcopropene (1-MCP), pre-conditioning, or 1-MCP + pre-conditioning on fruit quality attributes and incidence of physiological disorders in ‘Wonhwang’ pears stored at commercial storage facility and then shipped to Taiwan from South Korea. GA4+7 treatment reduced fresh weight loss but was lowered flesh firmness compared with the other treatments. 1-MCP treatment maintained superior fruit firmness during shelf life relative to other treatments. Soluble solids concentration (SSC) did not differ among treatments. Titratable acidity (TA) was lowest in GA4+7 treatment but relatively retained in 1-MCP treatment, compared with the other treatments. Lightness (L*) was not affected by treatments among tissues during shelf life but was higher in 1-MCP treatment than in pre-conditioning or GA4+7 treatments. Peel staining was only detected in GA4+7 treated fruit. 1-MCP treatment reduced the severity of flesh browning, core browning, water soaking and cavity, compared with the other treatments. Overall, the results suggested that 1-MCP treatment to early season ‘Wonhwang’ Asian pears enables the retention of fruit firmness and reduces the severity of physiological disorders for international trading, compared with GA4+7 or pre-conditioning treatments.