List of peach and nectarine diseases facts for kids

Peaches and nectarines are delicious fruits, but just like us, their trees can get sick! This article is about the different kinds of diseases that can affect peach (Prunus persica) and nectarine (P. persica var. nucipersica) trees. Knowing about these diseases helps farmers and gardeners keep their trees healthy and grow lots of yummy fruit.

Bacterial Diseases: Tiny Trouble Makers

Bacteria are super tiny living things, so small you need a microscope to see them! Some bacteria can cause diseases in peach and nectarine trees.

• Bacterial Canker: This disease is caused by a type of bacteria called Pseudomonas syringae. It creates open sores or "cankers" on the branches and trunk of the tree. These cankers can ooze a gummy substance.
• Bacterial Spot: Caused by Xanthomonas pruni, this disease makes small, dark spots on the leaves, fruit, and twigs. The spots on leaves might fall out, making the leaf look like it has "shot holes."
• Crown Gall: This disease, caused by Agrobacterium tumefaciens, makes rough, tumor-like growths called "galls" on the roots or lower trunk of the tree. It can make it hard for the tree to get water and nutrients.
• Phony Disease: Caused by Xylella fastidiosa, this disease makes the tree grow slower and produce smaller, less tasty fruit. The leaves might also look darker green than usual.

Fungal Diseases: Spreading Spores

Fungi are another type of living organism, like mushrooms or mold. Many plant diseases are caused by fungi, which often spread through tiny spores carried by wind or water.

• Brown Rot: This is a very common and serious disease for peaches and nectarines, caused by fungi like Monilinia fructicola. It attacks the blossoms, making them wilt and turn brown. It also causes the fruit to rot, turning it soft and brown with fuzzy gray mold.
• Leaf Curl: If you see peach leaves that are thick, bubbly, and reddish-purple, it's probably leaf curl! This disease is caused by the fungus Taphrina deformans. It can make the leaves fall off early.
• Powdery Mildew: This disease looks like a white, powdery coating on the leaves, twigs, and fruit. It's caused by fungi like Podosphaera clandestina. It can make the fruit rough and discolored.
• Scab: Caused by Cladosporium carpophilum, scab creates small, dark, fuzzy spots on the fruit. These spots can make the fruit look bad and sometimes crack.
• Shot Hole: Similar to bacterial spot, this fungal disease (caused by Wilsonomyces carpophilus) also makes small spots on leaves that eventually fall out, leaving holes. It can also affect fruit and twigs.
• Silver Leaf: This disease, caused by Chondrostereum purpureum, makes the leaves look like they have a silvery sheen. It can cause branches to die back.
• Verticillium Wilt: Caused by Verticillium dahliae, this fungus lives in the soil and can block the tree's water pipes, making branches or even the whole tree suddenly wilt and die.

Ripe Fruit Rots: After the Harvest

Even after you pick them, peaches can still get sick! These fungi cause problems for fruit that is ripe or stored.

• Aspergillus Rot: Caused by Aspergillus niger, this rot makes soft, watery spots on the fruit, often with black mold.
• Blue Mold: This rot, caused by Penicillium species, creates soft, watery spots with blue-green mold.
• Botrytis Rot: Caused by Botrytis cinerea, this rot makes soft, brown spots with gray mold.
• Rhizopus Rot: A very fast-spreading rot caused by Rhizopus stolonifer, it makes fruit very soft and watery, often with fuzzy black mold.

Nematodes: Tiny Worms in the Soil

Nematodes are microscopic roundworms that live in the soil. Some of them are parasitic, meaning they feed on plants and can cause damage to the roots of peach trees.

• Dagger Nematode: These nematodes (like Xiphinema americanum) can damage roots and also spread certain plant viruses.
• Lesion Nematode: Pratylenchus vulnus is an example of a lesion nematode. They create small brown spots or "lesions" on the roots, which can hurt the tree's ability to take up water and nutrients.
• Root Knot Nematode: These nematodes (like Meloidogyne incognita) cause the roots to swell and form "galls" or knots. This makes it hard for the tree to grow properly and get enough water.

Viral Diseases: Invisible Invaders

Viruses are even smaller than bacteria and can cause many different problems for plants. They are often spread by insects or through grafting.

• Peach Mosaic Virus: This virus causes a patchy, mosaic-like pattern on the leaves. It can also make the fruit smaller and bumpy.
• Plum Pox (Sharka): This is a very serious viral disease caused by the Plum pox virus. It causes rings and spots on leaves and fruit, and can make the fruit misshapen and fall off early.
• Prunus Necrotic Ringspot Virus (PNRSV): This common virus can cause ringspots on leaves, stunted growth, and can reduce fruit yield.
• Tomato Ringspot Virus (ToRSV): This virus can cause problems like "Prunus stem pitting," where pits or grooves form in the wood of the tree's trunk and branches.

Phytoplasma Diseases: Plant Bacteria Hybrids

Phytoplasmas are special types of bacteria that live inside plant cells. They are often spread by insects that feed on plant sap.

• Little Peach and Yellows: These diseases are caused by phytoplasmas and can make the tree's growth stunted, leaves turn yellow, and fruit become small and ripen poorly.
• X-Disease: This phytoplasma disease causes leaves to turn reddish-orange, curl, and fall off early. It can also cause branches to die back.

Miscellaneous Problems: A Mix of Troubles

Sometimes, tree problems are caused by a mix of things, not just one type of germ.

• Peach Tree Short Life: This is a complex problem where peach trees suddenly die, often when they are young. It can be caused by a combination of things like cold weather damage, certain nematodes, and bacterial or fungal cankers.