The mealybug, Phenacoccus solenopsis (Hemiptera: Coccomorpha: Pseudococcidae), is one of the main pests attacking maize plants in Egypt. Field trials were carried out in the maize field to assess the influence of irrigation periods and potassium fertiliser rates on the mealybug ( P. solenopsis) population estimates, vegetative growth, resulting yield, and its components for the maize cultivar (‘Single-Hybrid 168 Yellow’) in the Luxor Governorate, Egypt. Results revealed that unfertilised plants irrigated every seven days had higher pest population densities than other treatments over the two seasons. The fertilised treatments at 114 kg K ₂O∙ha ^–1 that received water every 10 days had the smallest population of P. solenopsis in every season. Data during the two seasons (2021 and 2022) revealed that the maize to which potassium fertiliser was added by 114 kg K ₂O∙ha ^–1 and irrigated every 10 days had vegetative growth (plant height, diameter, and number of green leaves per plant), yield and its components (average ear length, ear weight, number of grains per ear, weight of 1000 grains, and grain yield) significantly increased as compared to those of the plants that were irrigated every 7 days and without adding fertiliser. A higher dose of potassium fertiliser reduces the infestation of P. solenopsis but causes an increment of maize vegetative growth. This affects the final yield. This information aids farmers in comprehending the good agronomic techniques of maize plants to decrease the infestation of mealybugs and increase the yield.

Mineral fertilisers are one of the most important nutrients that plants need in large quantities, which help to greatly increase crop yields, and yeast is considered a bio-stimulator of plants. However incorrect implementation of both can make them more susceptible to pest infestations. The mealybug, Phenacoccus solenopsis (Hemiptera: Pseudococcidae), is an economically important polyphagous pest that destroys okra plants in Egypt. This work focused on the evaluation of mealybug infestations and okra plant productivity responses to mineral fertilisers (nitrogen and phosphorus), yeast (without and with) and their interactions. This study was executed in a private okra field (‘Balady’ cultivar) in Luxor Governorate, Egypt, during 2021 and 2022 seasons. A split plot design was applied, where two levels (with and without yeast) were used in the main plots, where seven levels of nitrogen and phosphorus were applied in the split plots. The results indicated that the addition of 286 kg N∙ha ^–1, 143 kg P∙ha ^–1 and yeast to okra plants led to a maximum increase in the population densities of pest, and this caused a decrease in the vegetative stage of okra that would affect the final yield as compared to the other treatments throughout the two seasons. However, the application of 190 kg N∙ha ^–1, 107 kg P∙ha ^–1, and yeast to okra plants gave the highest values for vegetative growth characteristics and resulting yield during the two studied seasons. This work aids farmers in improving okra production by comprehending good farming practices and avoiding the spread of mealybugs.