Garlic Diseases and Pests

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Rust (Puccinia Porri)

Rust is a fungal garlic plant disease that is spread through the air and condusive to high humidity and low rain fall. The garlic will show small yellow and white spots that will turn into small orange blisters. The bulbs will often be deformed and small. If you see this you can increase the levels of sulphate or potash into the ground around the plants and spray with Sulphur compounds or Dithane for prevention.

White Rot (Sclerotium Cepivorum)

This is also a fungal plant disease but it is soil borne and it is connected to the cultivation of the garlic. Early signs of this disease can be a white cotton like mycelium growth on the stem plate and soon after all the leaves on the plant will turn yellow and die. You can remove the plants and soil from the area but this can stay in the soil for over 20 years and you will not be able to grow any more of the garlic here. This is one of the most devastating disease for garlic crops.

Purple Blotch Fungi Alternaria porri and Stemphylium leaf blight: Stemphylium vesicarium

Plants that get this disease occurs with wet foliage and during nights of high humidity. Small wet lesions can be seen on the leaves or stalks. These lesions have white centers and eventually turn to brown and purple in color surrounded by yellow. These lesions can grow to eventually cause the leaf to die and then the entire garlic. This is mostly on onions but can affect garlic. Long rotations of different crops that are unaffected by this is recommended as well as having well drained soil.

Fusarium (basal or bottom rot)

This is a fungus that is usually in all soils and it will affect plants that are already in poor shape due to other diseases or insects or any other reason. It is more apparent in high temperatures. The symptoms are similar to white rot however it takes a longer time for the disease to show itself and there is the possibility that the plant will not die. Bulbs that have this disease can continue to break down while in storage as well. You can control this disease by crop rotation with crops that cannot get this disease.

Pink Root

This appears in warm weather and it is a fungus that causes the roots of the garlic to turn pink. They will then die. Sometimes you can see this on the plant with a leaf tip burn. To control this disease you need to use crop rotation for at least 3-5 years.


This is also a fungus that will affect the garlic leaves and also the stems. This disease is sometimes called neckrot as well. This can occur after periods of warm wet weather when the stems have been completely water soaked in warm temperatures. There can be a mild infection or it can lie in wait in the garlic and then affect the bulb in storage. When it is severe the bulb will rot. To control this disease you need to have soil and movement of air through the garlic plants so that after wet periods they can dry out quickly. Also to stop this from affecting bulbs in storage it is best to have a place they can dry quickly after being harvested as well a good air flow through your storage facility while they are drying.

Penicillium Molds

This disease is spread through the air and can be found in the fields or also in storage. It starts as an infected clove planted and then will spread. Plants that start growing in the spring, when affected with this disease, will turn yellow and then die. Often times you can see a bluish greenish color on the cloves in the soil as well as during storage. Do not use the cloves for planting again if you see this disease on your garlic plant. Wash your hands after touching this plant and the bulbs.

Bloat nematode

These are microscopic round worms. These feed off of plants and usually live some of its life in the soil. It lives and feeds insides the bulbs, and leaves, and stems of onions and garlic. Because the bloat nematode can withstand extremely dry conditions it can survive for years in crops that have been infected and can be easily spread through water run off and contaminated soil, equipment, seeds, and plants.

Planting seed that is free of nematodes as well as planting in areas free from nematode will stop the spread. Also a technique of dipping the affected seed into hot water 110-112 F for 10-20 minutes before planting will help although if not using other additives it is not usually that affective. Horticultural cornmeal as been suggested that it can be applied as a top dressing to the soil at the rate of one pound per 100 square feet is to reduce soilborne nematode populations, as is growing brassicas (mustard, cabbage, etc.) and tilling the green plants under the soil before planting the garlic or onions.

Some other ideas of stopping fungal diseases or nematodes or mites is soaking in a few different solutions. There are different solutions of using a gallon of water with baking soda, liquid seaweed and alcohol. These can be adjusted to the problem that you are dealing with and tweaked into different ways and solutions.


These are the garlic plant’s most common pest. They suck the moisture and the chlorophyll from the plants, gradually slowing growth and bulb production. Several ways to take care of them are to spray the plants well with a hose to knock off the pests from the plant. Using an organic pesticide on the plants could be a way to help control this pest as well as spreading a nitrogen based fertilizer around the base of the plants, reapplying when needed throughout the season. Planting crops that do not attract thrips around your garlic and onions is also an important tip. Grains attract the thrips so planting flowers or vegetables would be very helpful. Mulching around the plants will cool the temperature as well as encourage predators that eat the thrips.

Onion Fly

This is an popular garlic pest. It will lay eggs in the base of the plant near the roots and will eat the plant until it dies. Get rid of the plant as soon as you can and there are suggestions of spraying ginger, chili powder and cayenne pepper can prevent the laying of eggs.


Mites often will live on the bulb together and near the roots of the garlic. These mites will stop your plant from growing tall and can greatly reduce your harvest. They can live season to season so it is best to rotate the plantings and skipping onion or garlic plantings in the same space for each season.

Leaf Miners

These pests lay their eggs in the leaf tissue. They are small off white larvae that will eat the leaves causing visible damage. They are not a great damage to the bulb of the garlic.

Wheat Curl Mites

These mites cause more damage as they can cause the bulb to dry out and cause the leaves to be stunted and curled. They can also encourage the yellow streak virus. Before planting if you soak the seed garlic in hot water it can help eliminate these mites.

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