Editing Cabbage (section)

===Cultivation problems===
Due to its high level of nutrient requirements, cabbage is prone to [[micronutrient deficiency|nutrient deficiencies]], including [[Boron deficiency (plant disorder)|boron]], [[Calcium deficiency (plant disorder)|calcium]], [[Phosphorus deficiency|phosphorus]] and [[Potassium deficiency (plants)|potassium]].<ref name=Brad56/> There are several physiological disorders that can affect the postharvest appearance of cabbage. Internal tip burn occurs when the margins of inside leaves turn brown, but the outer leaves look normal. Necrotic spot is where there are oval sunken spots a few millimeters across that are often grouped around the midrib. In pepper spot, tiny black spots occur on the areas between the veins, which can increase during storage.<ref>{{cite web |title=Nonpathogenic Disorders of Cabbage |url=http://vegetablemdonline.ppath.cornell.edu/factsheets/Crucifers_Nonpathogenic.htm |author1=Becker, Robert F.  |author2=Bjorkmann, Thomas |publisher=Cornell University: Department of Plant Pathology |work=Vegetable MD Online |access-date=2013-08-30}}</ref>

Fungal diseases include [[Rhizoctonia solani|wirestem]], which causes weak or dying transplants; [[Fusarium|''Fusarium'' yellows]], which result in stunted and twisted plants with yellow leaves; and [[Blackleg (Brassica)|blackleg]] (see ''[[Leptosphaeria maculans]]''), which leads to sunken areas on stems and gray-brown spotted leaves.<ref name=Brad57/> The fungi ''[[Alternaria brassicae]]'' and ''[[Alternaria brassicicola|A.&nbsp;brassicicola]]'' cause dark leaf spots in affected plants. They are both seedborne and airborne, and typically propagate from spores in infected plant debris left on the soil surface for up to twelve weeks after harvest. ''[[Rhizoctonia solani]]'' causes the post-emergence disease wirestem, resulting in killed seedlings ("damping-off"), root rot or stunted growth and smaller heads.<ref name="Keinath2007">{{cite book |author1=Keinath, Anthony P. |author2=Cubeta, Marc A. |author3=Langston Jr., David B. |chapter=Cabbage diseases: Ecology and control |title=Encyclopedia of Pest Management |volume=2 |year=2007 |editor-last=Pimentel, David |publisher=CRC Press |pages=56–59 |isbn=978-1-4200-5361-6}}</ref>

[[File:Groene savooiekool schade van kooluil (Mamestra brassicae damage).jpg|thumb|right|[[Cabbage moth]] damage to a savoy cabbage]]

One of the most common bacterial diseases to affect cabbage is [[black rot]], caused by ''[[Xanthomonas campestris]]'', which causes [[chlorosis|chlorotic]] and [[necrosis|necrotic]] lesions that start at the leaf margins, and [[wilting]] of plants. [[Clubroot]], caused by the soilborne [[slime mold]]-like organism ''Plasmodiophora brassicae'', results in swollen, club-like roots. [[Downy mildew]], a parasitic disease caused by the [[oomycete]] ''[[Peronospora parasitica]]'',<ref name="Keinath2007"/> produces pale leaves with white, brownish or olive [[mildew]] on the lower leaf surfaces; this is often confused with the fungal disease [[powdery mildew]].<ref name=Brad57/>

Pests include [[root-knot nematode]]s and [[Delia radicum|cabbage maggot]]s, which produce stunted and wilted plants with yellow leaves; [[aphid]]s, which induce stunted plants with curled and yellow leaves; [[harlequin cabbage bug]]s, which cause white and yellow leaves; [[thrip]]s, which lead to leaves with white-bronze spots; [[striped flea beetle]]s, which riddle leaves with small holes; and [[caterpillar]]s, which leave behind large, ragged holes in leaves.<ref name=Brad57>[[#Bradley|Bradley et al.]], pp. 57–59</ref> The caterpillar stage of the "small cabbage white butterfly" (''[[Pieris rapae]]''), commonly known in the United States as the "imported cabbage worm", is a major cabbage pest in most countries.<ref name="Finch2007"/>

The large white butterfly (''[[Pieris brassicae]]'') is prevalent in eastern European countries. The diamondback moth (''[[Plutella xylostella]]'') and the cabbage moth (''[[Mamestra brassicae]]'') thrive in the higher summer temperatures of continental Europe, where they cause considerable damage to cabbage crops.<ref name="Finch2007"/> The mustard leaf beetle (''[[Phaedon cochleariae]]''), is a common pest of cabbage plants.<ref>{{Cite journal |last1=Gross |first1=Jürgen |last2=Müller |first2=Caroline |last3=Vilcinskas |first3=Andreas |last4=Hilker |first4=Monika |date=November 1998 |title=Antimicrobial Activity of Exocrine Glandular Secretions, Hemolymph, and Larval Regurgitate of the Mustard Leaf BeetlePhaedon cochleariae |url=https://linkinghub.elsevier.com/retrieve/pii/S0022201198947814 |journal=Journal of Invertebrate Pathology |language=en |volume=72 |issue=3 |pages=296–303 |doi=10.1006/jipa.1998.4781 |pmid=9784354|url-access=subscription }}</ref> The mustard leaf beetle will often choose to feed on cabbage over their natural host plants as cabbage is more abundant in palatable compounds such as glucosinolates that encourage higher consumption.<ref name=":2">{{Cite journal |last1=Müller |first1=Thorben |last2=Müller |first2=Caroline |date=24 August 2015 |title=Behavioural phenotypes over the lifetime of a holometabolous insect |journal=Frontiers in Zoology |volume=12 |issue=1 |pages=S8 |doi=10.1186/1742-9994-12-S1-S8 |issn=1742-9994 |pmc=4722364 |pmid=26816525 |doi-access=free}}</ref> The cabbage looper (''[[Cabbage looper|Trichoplusia ni]]'') is infamous in North America for its voracious appetite and for producing frass that contaminates plants.<ref>Turini TA, Daugovish O, Koike ST, Natwick ET, Ploeg A, Dara SK, Fennimore SA, Joseph S, LeStrange M, Smith R, Subbarao KV, Westerdahl BB. Revised continuously. ''UC IPM Pest Management Guidelines Cole Crops.'' UC ANR Publication 3442. Oakland, CA.</ref> In India, the diamondback moth has caused losses up to 90 percent in crops that were not treated with insecticide.<ref>[[#Janick|Janick]], p. 195</ref> Destructive soil insects such as the cabbage root fly (''[[Delia radicum]]'') has larvae can burrow into the part of plant consumed by humans.<ref name="Finch2007">{{cite book |author1=Finch, Stan |author2=Collier, Rosemanry H. |chapter=Cruciferous root crop insects: Ecology and control |title=Encyclopedia of Pest Management |volume=2 |year=2007 |editor-last=Pimentel, David |publisher=CRC Press |pages=131–134 |isbn=978-1-4200-5361-6}}</ref>

Planting near other members of the cabbage family, or where these plants have been placed in previous years, can prompt the spread of pests and disease.<ref name=Brad56/> Excessive water and excessive heat can also cause cultivation problems.<ref name=Brad57/>

Factors that contribute to reduced head weight include: growth in the compacted soils that result from [[no-till farming]] practices, drought, [[waterlogging (agriculture)|waterlogging]], insect and disease incidence, and shading and nutrient stress caused by weeds.<ref name="Wien and Wurr 533"/>