Category: Fact Sheets

Disease(s): Common Foliar Diseases of Alliums This fact sheet discusses botrytis leaf spot (Botrytis squamosa), purple blotch (Alternaria porri), stemphylium leaf blight (Stemphylium vesicarium) and downy mildew of onion (Peronospora destructor). These are the most commonly occurring foliar diseases of alliums in the Northeast, and many of their disease dynamics are closely linked; if one

Pest: White mold (Sclerotinia sclerotium) Pest/disease lifecycle, most common damage symptoms and crops affected: White mold (Sclerotinia sclerotium) is a widespread disease of over 300 species of plants. It is only a sporadic problem in “normal” and dry growing seasons; however, white mold can be very damaging in wet years and, if it goes unrecognized

Pest: Slugs and Snails Pest/disease identification and lifecycle, most common damage symptoms and crops affected: Land slugs and snails are closely related mollusks, known together as “gastropods,” the primary difference between them being that snails have external spiraling shells. There are over 90 terrestrial gastropods found in Maine. The gray garden slug is most common

Pest: Two-spotted spider mites (Tetryanchus urticae) Pest/disease identification and lifecycle, most common damage symptoms and crops affected: Two-spotted spider mites are the most common mite pest of crops in the Northeast. Because they thrive in hot and dry conditions, they are commonly found in greenhouses and high tunnels. Spider mites can feed on many crops

Pest: Mexican bean beetle (Epilachna varivestis) Pest/disease identification and lifecycle, most common damage symptoms and crops affected: If Mexican bean beetles have historically been a problem on your farm or in your garden, you will very likely see them again this year. They may be pests on snap beans, dry beans, soybeans and lima beans.

Pest: Tomato Brown Rugose Fruit Virus (ToBRFV) Disease identification: Tomato brown rugose fruit virus, otherwise referred to as ToBRFV, is a highly virulent and aggressive plant virus that can cause serious infections on tomato and pepper species. ToBRFV behaves very similarly to other tobamoviruses such as ToMV (tomato mosaic virus) and TMV (tobacco mosaic virus).

Pest: Allium Leafminer (Phytomyza gymnostoma) Pest/disease identification and lifecycle, most common damage symptoms and crops affected: Allium, or onion, leafminer (ALM) is an invasive pest of alliums. Adult allium leafminers are small (approximately 3 millimeters) gray/black flies with a distinctive orange/yellow spot on the tops of their heads, and yellow “knees” (Fig. 1). ALM have

Condition: Waxy Breakdown (an abiotic disorder) Pest/disease identification and lifecycle, most common damage symptoms and crops affected: Waxy breakdown of garlic is a physiological condition that sometimes affects garlic, though typically only rarely in Maine. Development of the condition is not fully understood but often associated with very high temperatures and/or sunscald damage around harvest

Disease: Powdery Mildew of Cucurbits (Podosphaera xanthii and Erysiphe cichoracearum) Pest/disease identification and lifecycle, most common damage symptoms and crops affected: Management options: Powdery mildew is a common disease of pumpkins and winter squash. All cucurbits are susceptible, but many common cucumber and melon varieties have had powdery mildew resistance bred into them. The disease

Pest: Hornworms (Manduca sexta, M. quinquemaculata) Pest/disease identification and lifecycle, most common damage symptoms and crops affected: Hornworms are probably the most destructive insect that attacks tomatoes. They are giant caterpillars that grow rapidly and can do a vast amount of eating in a very short amount of time. Sometimes it seems that healthy-looking tomato