Most pests that afflict pepper plants are regional, so some may be present in your area and some may not. Most are external feeders, meaning they are visible outside of the plant (or at least their effects are). A few leaf miners or borers are also around, of course.
The beet armyworm and tobacco brownworm are both caterpillars that affect pepper plants. They are both a greenish color with the beet armyworm being darker and sometimes almost black. These caterpillars are 30mm and 90mm respectively and will be easily seen with the naked eye.
They are easily controlled by encouraging birds in the garden or through pest control methods such as diatomaceous earth.
Two hard-bodied insects, flea beetles and pepper weevils, can infest pepper plants. Flea beetles are in fact several species of tiny, darkly-colored pests. Pepper weeviles, similarly, are reddish-brown beetles of about the same size as fleas. Both types of beetle are made obvious by their small, circular holes left behind in foliage, buds and pods.
Both are also easily controlled through spiders or diatomaceous earth. Some soap-based pesticides also work well to keep these pests at bay.
Other pests include the green peach aphid, the potato leafhopper, the corn earworm, and the fall armyworm. All are controlled through the above-mentioned methods.
Sunscald on Peppers
This problem occurs when peppers (the fruit of the plant) are suddenly exposed to intense sunlight, high temperatures, and high humidity. It creates white, soft, sunken and wrinkled areas on the peppers and potentially ruins their flavor. It can also be a contributor to blossom end rot (below).
The most common causes of sunscald are loss of foliage cover (often from defoliation or wilting) or heavy rains that expose the fruits. Most of the time, this is a final symptom of an underlying nitrogen depletion problem. Properly nitrogenated soils usually keep healthier plants that do not see sunscald unless physical intervention (overspray from herbicides or clumsy machinery) causes the defoliation.
Pepper Blossom Drop
Flower or blossom drop is a common problem for pepper gardeners. The most common causes are all related in that the plant realizes that it cannot produce fruits under current conditions, so it stops doing so. Common reasons are: temps too high or low (over 95F, under 65F), too much nitrogen in the soil, too much water, not enough light (sun or artificial), and restricted roots. Some problems are inherent only for indoor/hydroponics growers and include poor air circulation, not enough light intensity, and too much minerals in the nutrient base water.
All of these problems have obvious fixes. For most gardeners, the most likely issue will be nitrogen or water. Temperatures can be controlled with covers temporarily, of course.
Pepper Blossom End Rot
As its name implies, this is when the tips or ends of the peppers rot or fall away. They become sunken, watery, and rotten appearing. The peppers are still edible if this is cut off, but it’s unsightly and makes the peppers unmarketable. Common causes of blossom end rot include salty soil, inconsistent watering, smothered roots (overwatering), and occasionally by fruits that dip down to touch the soil when its moist.
Obviously, consistent watering is a must with pepper plants. Over or under-watering causes end rot faster than any other issue.
Most favorite varieties of peppers are resistant to the common viruses that can plague the plants. Most plants have been bred to avoid disease. Common viruses for peppers include alfalfa mosaic, bacterial spot, cucumovirus, curly top, impatiens necrotic spot, pepper potyvirus, pepper tobamovirus, phytophthora root and crown rot, powdery mildew (common in many plants), tomato spotted wilt virus, and verticillium wilt.
Nearly all of these are due to poor growing conditions, usually involving heat or water. Most can be avoided if proper watering and temperature control is maintained. Some, such as powdery mildew and pepper potyvirus, can be controlled through sprays or soil treatments as well.