Elevated temperatures associated with climate change result in crops being exposed to frequent spells of heat stress. Heat stress results in reduced yield in field pea (Pisum sativum L.); it is therefore important to identify cultivars with improved pod and seed retention under heat to mitigate this loss. Objectives were to investigate the effect of heat stress on phenology, yield and pod‐based yield components. Sixteen pea cultivars were evaluated at normal and late (hot) seeding dates in the field in Arizona 2012 and in growth chambers with two temperature regimes (24/18°C and 35/18°C day/night temperature for 7 days) during reproductive development. We measured variation in the pattern of pod retention at four‐node positions on plants, seed retention by ovule position (stylar, medial and basal) within pods and screened cultivars for pod retention, seed retention and yield. Heat stress reduced seed yield by accelerating the crop lifecycle and reducing pod number and seed size. Heat stress had the most damaging effect on younger reproductive growth (flowers and pods developed later), resulting in ovary abortion from developing flowers. Heat also accelerated seed abortion in all ovule positions within pods. Two high‐yielding cultivars under control temperature, “Naparnyk” and “CDC Meadow”, maintained high yield in heat, and “MFR043” had the lowest yield. Cultivars “40‐10” and “Naparnyk” retained the most ovules and seeds per pod, and “MFR043” aborted seeds when exposed to heat. In half of the cultivars, ovules at the basal peduncle end of pods were likely to abort while ovules at the medial and stylar end positions developed into seeds. For seven of the field cultivars, ovules at the medial pod position also produced mature seeds. Cultivars “40‐10”, “Naparnyk” and “CDC Meadow” had greater pod and ovule retention or maintained high yield under heat stress, and were identified as heat‐tolerant cultivars. Our results allow for a better understanding of pod‐based yield components in field pea under heat stress and developing heat‐tolerant cultivars.

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Apple production in the Fes-Meknes region of Morocco is highly affected by pests and adverse weather conditions. A survey of apple farmers’ knowledge, perceptions and practices (KPP) in pest management and climate change was conducted in spring 2018 in two major apple-producing provinces of the region. Each farmer reported three insect pests and two diseases on average affecting their orchards. Pest management was performed by a combination of cultural and chemical methods. All farmers used dormant chemical sprays. About 60% of the respondents adopted pest surveillance based on visual inspection and 41.9% chose their pesticides on the basis of the information received from pesticide sellers. An average of 20 treatments per year was applied in each orchard. Regression analysis showed that neither the age of apple trees nor the number of pesticide applications influenced yield. Adverse weather conditions affected all apple plantations and the most frequent problems perceived were frosts, hailstorms, hot winds and water shortage. Of the orchards reported, 51.3% were protected with anti-hail nets. In order to reduce the rate of pesticide applications, better information on integrated pest management is required. Introduction of organic farming is necessary as 40.5% of the farmers agreed to convert to this practice in the future provided that market facilitation is established.

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The effects of applied nitrate on symbiotic nitrogen fixation in legumes are complex. Both inhibition and promotion of nodulation by nitrate have been observed in a dose‐dependent manner. The objectives of this study were to determine the effects of nitrate at different concentrations on root nodulation in different genotypes in common bean (Phaseolus vulgaris). Six genotypes were inoculated with the same rhizobial strain and grown hydroponically in growth pouches in a growth chamber and exposed to six nitrate concentrations, including 0, 2.5, 5, 10, 15, and 20 mM for 4 weeks. The tested genotypes included three recombinant inbred lines (RILs, 25, 46, and 70) that differed in their responses to nitrogen (based on observations of one field growing season), their parents (Mist and Sanilac—registered varieties), which are different in N‐fixing abilities, and one nonnodulating mutant (R99). Our results showed that small amounts of nitrate (2.5 and 5 mM) promoted nodule formation and increased nodule biomass, compared with plants in the 0 nitrate control treatment. In contrast, nitrate concentrations over 10 mM inhibited nodulation, resulting in reductions in nodule number and nodule biomass. Nodulation was completely inhibited by 15‐mM nitrate in all the genotypes. Regression analyses indicated that 5‐mM nitrate is the optimum concentration for promoting nodulation as measured by the total number of nodules formed, the number of effective nodules formed, and the nodule biomass formed. In contrast, nitrogen fixation was inhibited by all levels of nitrate. No genotypic differences were observed in nodulation among the three RILs and their parental cultivars, but all were significantly different than R99, a nonnodulating mutant.

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An extensive survey conducted in the Saïss plain of Morocco during the 2017–2018 growing season revealed that 35 out of 50 apple and pear orchards were infested with a pathogen that causes the decline disease. Morphological and phylogenetic tree analyses using the cox II gene allowed us to identify the pathogen as Phytopythium vexans. Interestingly, no Phytophthora and Pythium species were isolated. The occurrence and prevalence of the disease varied between locations; the most infested locations were Meknes (100%), Imouzzer (83%), and Sefrou (80%). To fulfill Koch’s postulate, a greenhouse pathogenicity test was performed on the stem and collar of one-year-old healthy seedlings of apple rootstock M115. Symptoms similar to those observed in the field were reproduced in less than 4 months post-inoculation with root rot disease severity ranging from 70 to 100%. The survey results evidenced that apple rootstocks, soil type, and irrigation procedure may contribute significantly to the occurrence of the disease. The disease was most prevalent in drip water irrigation and sandy-clay soil on wild apple rootstock. Accordingly, a rational drip advanced watering system and good sanitation practices could eliminate water stagnation and help prevent the onset of this disease. It was concluded that Pp. vexans occurrence may be strongly influenced by irrigation mode and type of soil. Therefore, the obtained findings of this study could help to better understand the recurrence of this disease and to develop a reliable integrated strategy for its management.

Apple scab, Venturia inaequalis (Cooke) G. Winter, results in numerous fungicide applications in the Sais region of Morocco. We conducted the study to determine the susceptibility of cultivars through field survey and to evaluate the sensitivity of V. inaequalis to three fungicides using both in vitro and in vivo methods. We surveyed 100 apple orchards and collected two samples. Disease survey showed that the cultivars were highly susceptible to apple scab (grand mean of leaf scab: Golden Delicious, 40.31%; Starking Delicious, 20.45%; and Gala, 18.92%). Results underlined no significant differences between isolates in term of inhibition rate of mycelial growth and averaged disease severity. However, both treatment and concentration were statistically significant. EC50 values ranged from 2.33 µg/ml to 7.40 µg/ml and resistance factor (RF) values of 0.55, 1.02 and 1.79 were obtained for difenoconazole, trifloxystrobin and thiophanate-methyl, respectively. In vivo tests at a concentration of 10 µg/ml on the isolate ViIF using a curative method showed a high efficacy of trifloxystrobin (96.38%), and low efficacy of thiophanate-methyl (29.65%) and difenoconazole (24.62%). V. inaequalis was most sensitive to trifloxystrobin followed by difenoconazole and thiophanate-methyl, respectively. From this work, it was recommended testing more isolates and contact fungicides in order to develop a baseline sensitivity of the pathogen population against commonly used fungicides to treat the disease, as continued usage over time and the introduction of new fungal races may result in a decrease in fungicide efficacy.