Brown spots on apricots often indicate underlying issues affecting fruit quality. Understanding their causes is crucial for effective management and a healthy harvest.
Identifying Different Types of Brown Spots
Visually distinguishing different types of brown spots helps diagnose the problem. Spots can be small specks that enlarge, sunken, or flush with the surface. Texture varies from smooth to fuzzy, sometimes velvety.
Spot color ranges from pale green to dark brown or black, with possible reddish-brown or purple margins. Spots may cluster or merge into larger blotches. Their location (one side, near stem, or scattered) also provides clues.
Primary Causes of Brown Spots
Brown spots on apricots can stem from a variety of sources, including fungal and bacterial diseases, pest activity, and environmental stressors. Each cause typically leaves distinct marks on the fruit, requiring different approaches for management.
Fungal Diseases
Brown rot (Monilinia fructicola) causes soft, rapidly expanding brown spots on apricots. These spots often develop a tan or grayish, powdery mass of spores, leading to fruit rot and shriveling into “mummies” that may remain on the tree.
Apricot scab (Cladosporium carpophilum) appears as small, circular, greenish-brown or olive-green spots on the fruit surface. These superficial spots can coalesce into larger, velvety blotches, potentially causing fruit cracking.
Bacterial Diseases
Bacterial spot (Xanthomonas arboricola pv. pruni) causes small, dark, often angular spots on the fruit. Lesions may initially be water-soaked, deepening to dark brown or purple. Severe infections can pit or crack the fruit, creating entry points for other pathogens. This disease thrives in warm, wet conditions and can also cause a “shot hole” appearance on leaves.
Pests
Certain insects cause brown spots. The tarnished plant bug (Lygus lineolaris) feeds on developing fruit, causing raised or sunken corky areas and gummy ooze. Its feeding injuries lead to deformed fruit with deep pits or dimples. The oriental fruit moth also causes spots by boring into the fruit.
Environmental/Physiological Factors
Environmental conditions can also cause brown spots. Sunscald results from intense sunlight exposure, leading to flattened, discolored, brown areas on the exposed side.
Chill injury, a physiological disorder, develops when apricots are stored at certain cold temperatures, particularly between 2.2-7.6°C (36-46°F). Symptoms include water-soaked areas that turn brown, sometimes with sponginess or flesh browning around the pit.
Prevention Strategies
Proactive measures minimize brown spots. Sound cultural practices significantly reduce disease and pest risks.
Proper pruning ensures good air circulation and sunlight penetration, reducing moisture buildup that favors fungal and bacterial growth. Orchard sanitation is crucial; removing fallen fruit and diseased branches eliminates pathogen sources. Regularly cleaning up plant debris beneath trees is also beneficial.
Appropriate watering avoids excessive moisture. Drip irrigation or watering at the tree’s base is preferable to overhead watering, which spreads spores and creates humid conditions. Selecting disease-resistant apricot varieties offers defense against common issues like brown rot and bacterial spot. General protective sprays, such as fungicides or bactericides, can be applied preventatively during critical periods like bloom or early fruit development.
What to Do With Affected Apricots and Trees
When brown spots appear, managing the fruit and tree is important. Edibility depends on the cause and damage extent. Superficial spots from apricot scab or minor pest blemishes are often safe to eat once removed or peeled. However, apricots with extensive brown rot (soft, spreading decay, fuzzy mold) should be discarded. Bacterial spot, while unappealing, typically does not make fruit unsafe, though heavily affected areas may be unpalatable.
Managing tree problems involves removing and disposing of diseased fruit and branches to prevent pathogen spread. Promptly picking mummified fruits and pruning blighted twigs reduces infection sources. Disinfecting pruning tools between cuts avoids spreading diseases. After harvest, proper storage prevents new spots; apricots should be cooled promptly and stored at optimal temperatures (-0.5 to 0°C / 31-32°F) and 90-95% relative humidity. Storing fruit away from ethylene-producing fruits also helps maintain quality.